Some end-of-day blither for your consideration:
"Asked" is a light-sounding word, so it makes your tone go Up.
"Said", of course, is pronounced "sed"...a low tone that makes speech sound more flat. (aside: why does a speaker give a speech?)
"Asked" is implied, of course, by the question mark itself...strictly speaking, it is not necessary unless someone has not spoken for a while or you need to reintroduce someone to a conversation. "Said" might be used to indicate some kind of inflection.
If you opt for "said" with a question, you should have a compelling reason that matches the dialogue. It is more rhetorical.
Ex:
Todd appeared at Tanya's elbow, "They're just getting the plane ready now."
"How much longer?" she asked.
"Not long." Tanya glanced at her watch again, and resumed tapping her foot.
Ex:
Georgia rolled her eyes, "Do you think he can get some cope today?" she said under her breath as she heaved against the bumper.
Ex:
...and Janis had half a mind to hike up alone.
"How much longer?"
"Mebee an hour or two," once again Hank squeaked tobacco through his teeth, this time wiping green spittle off his chin.