Hosting out of town guests

Did you ask them to host your guests? If not, they’re doing the guests a favor, not you.

A nice idea but not necessary unless you asked them to like Catlyn said. It's up to the guests they are hosting to return the kind gesture. You could thank them in your Thank You cards, at the rehearsal dinner, or make mention during wedding speeches if you like.

If it fits in your budget I would. Maybe a favorite bottle of wine or a gift card to a favorite restaurant

If you asked them to host, definitely get them a gift. Even if it is small, it acknowledges their kindness and effort. Include a heartfelt note. I would think a gift cert to a restaurant or a bottle of wine would be nice if you have the budget, but even some homemade cookies or a bar of nice chocolate would do! I attended a college friend’s wedding and the bride’s neighbor let a bunch of us out of town guests stay at her home and she left for the weekend. I was young and it didn’t even occur to me to leave a gift for the family that hosted us. Luckily another of the guests brought some wine as a thank you gift. Your guests may or may not also provide a thank you but I still think a gift from you is important to show your appreciation for the favor.

If you didn’t make the arrangements then don’t give a gift or card.