I like getting my kids to wake naturally by getting them to bed early enough -- and making them responsible for getting themselves up and on the bus on time each morning. I don't let them have an alarm clock until at least 4th grade and then only to let them not worry that they might sleep in and not get up! Only my oldest child had to walk the mile to school a few times in 6th or 7th grade before he got better about getting up. (I walked that almost same mile myself to school as a child so I'm not cruel or allowing him to be in danger -- it's a good safe walk)
My Susy needs to have the alarm clock across the room so she has to physically leave her bed in order to not just turn it off and roll over and fall back to sleep.
Ido give my kids over age 11yo 3 emergency rides to school each year if for some reason they miss, but they know they only have 3 and will chose to walk if they miss the bus on a nice day so they have a ride left if they miss on a bad weather day!
A trick I've heard is to put a thermos of grapefruit or orange juice next to the alarm and have them drink that as soon as the alarm rings and hit the snooze button and then let them lie down until thealarm goes off again. Then they will feel energetic enough to get up from the sugar rush!