I've got a Snoozer II Lookout. Sophie LOVES it. It comes with a strap that can also hook to a harness so they'll be safe. I actually don't strap her in because she's more comfortable. I know, I know. I'm a BAD mommy!
But seriously, she has been soooo much better since I got that. She stays in the front seat and I put the AC on her so she'll get some air.