So, I have a huge life-changing exam in San Diego in Oct. I usually fly coach, but I figure this time around, the last thing I need is the stress of sitting between two people 3-times my size, with some bratty kid kicking me in the back every 2 minutes on a 4 hour flight.
The plan is to fly CLT-ATL-SAN and back. I'm trying to conserve on cash, so I was thinking that instead of flying paid first the whole way, I'd by 2 round trip tickets:
CLT-ATL in coach -- $150
ATL-SAN in first -- $1300
This works out much cheaper than the CLT-ATL-SAN first which is almost $1700

The problem is, I'm wondering -- 1. Would I have to check in twice? And if so, how do I manage that on the way back? (I'm thinking I'd have to go through security again in ATL...which gives me angina) 2. Is there some way I could combine the reservations after purchase (or purchase it the way I want in the first place). 3. Anyone have any other suggestions for how I could get away with this at a reasonable price?

I don't have enough miles for an upgrade, and I don't have any medallion status either


I'm sorry if any of this sounds like dumb newbie questions... but that's who I admittedly am right now. I really appreciate the help!