Hourly... and whatever I feel like. So long as people know when to expect me back and >1 hr lunches aren't a daily occurrence.
The one big benefit of my company is that they are pretty laid back about scheduling. If you have a doctor's appointment or something you just let someone know that you're going and you go. You don't really need to get approval and you don't get hassled for it.
For about 5 months now I've been coming in at 8, skipping lunch and leaving at 4. I get my 8 hours in for the day, I'm home before traffic hits, and I always feel like I have soooo much more free time in the evening because of it. Nobody has really cared and it's only been an issue once, where someone else waited until the last minute to turn a project over to me that needed done before EOD... they called me about 10 minutes after I left and I had to turn around and go back. I wasn't too happy about it because I ended up being stuck until 7 when this person could have given me the work earlier in the day and nobody would have had to work overtime. I haven't tested the waters with coming in at 7 or 7:30 and leaving at 3 or 3:30, but a lot of our deadlines are at 4, so I can imagine screwing myself over a lot.