I believe it was shown that Benadryl actually doesn't have the affect, statistically, that people want it to have on their wee ones. I couldn't do that to my kiddo, even if I knew it was absolutely going to work. I can barely give him western medicine when he NEEDS it, let alone to flat out drug the boy!
However, if you're into homeopathy at all, chamomile can be great, and if you've ever seen Rescue Remedy at various stores, it's WONDERFUL stuff. Works like magic...one second=freaking out child, next minute=everyone has forgotten that he was being wild b/c it was such a fast change. It also works on bickering adults (DH and I dose ourselves routinely while traveling).
*****
We have a travel carseat, the Scenera by Cosco, rather than hauling the Britax. We got a bag for it (Eddie Bauer brand from Target) b/c you're really not supposed to carry it by the straps, and it's difficult to carry otherwise. (you DO have to take it OUT of the bag for security)
When DS was 1.5 we just held him, and it was a bad experience (except that he did get to nurse when he wanted, which was good for everyone) b/c when he wasn't sleeping or nursing, he was a hellion. My arms were TIRED from holding him, and we couldn't rest.
Last year at 2.5, we had his seat, and it was SO much better. He's familiar with the seat, he's more buckled in, he can't squirm out of it. Very good things.
