It's amazing the difference a set of good tires can make on your wheelchair. This is true in your day to day getting around, especially for those of us who have to deal with snow. It's equally important I think though when you're traveling. You never know what kind of terrain you might run into or what the weather might hold. I'm looking at you always wrong 14-day forecast.
For the past 4 years I've been using Schwalbe Marathon Plus Evolution tires on my Ti-lite chair. They are hands down the best tires I've ever used. First they use a kind of black rubber that will outlast those standard grey tries by ages. I put a lot of distance on my chair every day and I can get a solid year out of these tires no problem. The ones on my chair right now are about 8 months old and showing some good wear. But it's been a cold winter with a lot of salt on the sidewalks around here. Next they have what Schwalbe calls Smartguard. This means that there is an extra thick strip of rubber where the tires touches the ground. This should make it much harder for you to get a puncture. I believe it because for example I've currently put large gashes in my tires that looks awful and yet they are still going without any breaks.
I will admit that these tires are not cheap. Their MSRP is about $63 USD each, so $126 per pair. However I do think it's worth considering how long they will last and how much you can put them through without getting a flat. Trust me dealing with a flat is the last thing you want to do while on vacation. The only other downside to these tires are they are a bit heavy. It's because of the extra rubber for the Smartguard feature. I don't really see it as a big deal but it's worth mentioning. They come in sizes from 22" up to 26".