dreaded vet visits

The first year with Ares has been a roller coaster of vet visits. I've been an overly anxious, overly cautious mom and he's had a couple of mishaps (accidentally getting kicked by a 12 year old who was playing tag with her brother and eating about 10 vitamins one night). He's fine and we've learned from our mistakes but each visit made him more and more apprehensive at the vet. He was great in the beginning and loved going but after getting a couple of fecal samples taken, going into the exam room made him cower and tuck his tail in between his legs.
I've actually worked really hard to keep the dogs from being afraid of the vet and I think I've succeeded because I try really hard to make it a positive experience. The biggest positive is that they LOVE car rides. They share the passenger seat in my car and sleep while I drive.
The other thing that I've done, mostly for Ares, is that I take him whenever Luna has to go. He gets to come and hang out with us and it's purely love and hugs for him from everyone. The first time at the vet for Luna's wellness check, he actually jumped up on the exam table and refused to get down! He waited calmly for his turn to get pets and hugs from the vet and left a happy little man.

It's a mute point now that I'm going every month right now for Luna, but I also get Ares' heart worm medication in 3 month supplies. He comes with me every time I pick up his medication even though we don't normally even weigh him (unless I request it). This will continue in the future because Luna won't be able to get huge supplies right now as she's still a growing puppy and they'll both continue coming with me as I pick up their medication.
I do this so they don't associate the vet as always being poked and prodded and being made to feel uncomfortable. I want them to continue to enjoy the vet so none of us dread the visits. It helps A LOT. (It may also help because there's a pet store nearby so we usually stop after we're done with the vet visit!)

Does anyone else have any tips for happy vet visits?