it depends, of course. generally, and this is just my opinion, most epic fantasy starts off slow, building up a little backstory involving a perfect shire, burrough, city, whatever, to illustrate why their world is worth saving before the innocent misfits are recruited for a long journey to destroy the great evil threatening their destruction. depending on how much the author feels he needs to pad his story depends on how long this goes on, but my experience is it doesn't go on for more than a good sized chapter out of a trilogy. then there are lots of references to some specifics along the way, invariably remembering the taste of some food, some event, or some virginal halfling babe with big knockers working at the tavern. that's just the kind of stuff i expect from traditional epic fantasy writing. (personally, were i to start one of those, and i probably will never do one, it'd start off with the hero on his deathbed and recalling the events that led to his mortal wound. you'd know from the get-go you're involving yourself with a character on his last legs and you'd read it anyway. sucker.) on occassion, it might start off with an ancient battle that sets up the current events, but that's pretty cheesy at this point.
single self-contained fantasy books i've read in the past few years (which have vastly been dominated by TSR (dungeons and dragons) publications), like to start off with a bit of action, like the thief doing his thing and making a narrow escape only to find out he is a she and she's the daughter of a prominant merchant. note that the epic has a longer ramp-up due to its ensemble nature, while following a character or two tends to be more action oriented.
how do you do both? well, you either have action from page one or you don't. is there a middle ground? you could focus on one of the ensemble characters as he's marching off to the final conflict, the din of battle in the distance, then go into flashback mode. you get a sense of impending action that way and the reader knows what to expect by the end without knowing the outcome. is that middle ground? obviously at some point you have to do some world-building. the reader may be curious to know why exactly one of the heroes are marching in the ranks of the orc army against the last bastion of goodness.
depending on what i read depends on how i expect the book to start. as a writer, what excites and challenges me most about the process is the arrangement of events. writing things out on a flat plane doesn't do much for me unless the idea demands it. otherwise, like in an epic fantasy, the only way i could possibly be enticed to write such a thing would be to play with its construction. for instance, i like the aftermath of an event. remember the beginning of 'pirates of the caribbean', where they come across a destroyed ship and the black pearl is escaping into the mist? that's a perfect beginning to me. it establishes characters, background, and sets up the mystery. what more could you ask? i love 'indiana jones'-style openings, too.
(come to think of it, the PotC opening is rather illogical. there are several unanswered questions i have there, but maybe they're answered in the movie and i just don't remember, heh heh. anyway....)
since i tend to go in for stories with a few characters, starting it off with some action works for me. you can do quite a bit of world and character building with action, action speaking louder than words and all that and 'show, don't tell'. that's really more the kind of thing i expect there.
really, though, i don't place too much emphasis on how the story starts either way. if your ship is spinning out of control, on trial for insubordination or he starts off in a cubicle or sitting on his front porch waiting for the wizard makes none to me if it's appropriate and that's what i'm in the mood for.
how do you please both groups? well, i reckon first you have to please yourself. i write what i want to write first, then take the reader into consideration, because if i start off writing only for them, there's no point putting my name of it. there are plenty of hacks out there who write simply to get published, which very much negates the reason for my literary existance if all i'm doing is trying to get my name out there and don't have any personal feelings for the thing, and i can't have any attachment to it unless i'm involved a lot deeper than being the conduit for cliche stories. i'd otherwise get into scratch model building as a diversion, lol.
eh, *shrugs shoulders*, either way works for me. as a writer i like to be a bit more inventive in the arrangement, though, if the story allows that. i *tend* to start off slow if it's a novel, but nearer to instant action for short stories. even then, though, i tend to focus on the tension in a situation than the action. anyone who's slogged through my 'the last outpost' in share your work can get an overall feeling for how i handle a short story (okay, a long short story). (you can also see why i don't write a lot of action, lol). in that, it's an alamo-impending-doom thing more than an action story. it was just a story that interested me with no regards with compensating to appeal to anyone else. i just find that when i start writing stories and begin making all sorts of compromises to it to suit what i think the reader expects, it turns out to be the reason why i stopped reading as much as i used to: that is, what's the point? i've certainly limited whatever potential readership i'd garner had i caved in and given everyone exactly what they want, but oh well, popularity clearly isn't high on my priority list, lol.
it raises an interesting question, doesn't it? i mean, compromise is a pretty big part of a relationship, this being the relationship between the writer and reader. so, to a certain extent, you *should* give 'em what they want, no? on the flip-side, this is my story and i'm telling it to you: this isn't a collaboration, take it for what it is or go to hell if you don't like it. i guess the balance there depends on how much of an artist you feel like being versus how much of a hack you are. no bonus points for guessing which side i put more weight on, lol. i don't tack on happy endings so the reader has fuzzy feelings in the end, nor do i start them off in any other way than it's because what the story dictates and it's the beginning i'm most interested in. consequently, i don't do the opposite just to be different.
i like reading both beginnings. i like writing both kinds. that's just one thing i look for when i open up a book. especially in the beginning i'm not expecting to be gripped hard, i'm more looking at style. i'm very tired and just blathering, so i'll stop now after meeting my sixty thousand words per post quota, heh heh.