Conference travel is really important for getting your name and your work out there, for networking, and for keeping up with what is really going on in the field that either is unpublishable or not published yet. As a lifelong introvert, I've really had to work at effective networking. It took me a while to figure out how to make the most of conferences. As I've gotten older, I find that I like the big society meetings less and less. A big meeting is huge, which means it is hard to just run into people, so key meetings have to be planned. Everyone is always running somewhere. The talk quality is highly uneven, especially since giving a quality 15-20 minute talk is really hard for an inexperienced person. Conferences always exhaust me, since I find spending so much time with people tiring, and the always on nature of a meeting is very draining. The endless busy-ness of a big meeting makes this worse for me.
As a student, I loved the wide range of topics, the exhibitions (with their swag) and the opportunity to put faces to the names on papers. Now that I am more established, I find that I am much happier to send my students to the big meetings, and attend smaller, more focused meetings myself. I still get energized from a good topical conference, and I love the opportunity to get up to speed quickly in a new direction by listening to expert talks rather than reading a lot of papers. That said, I find when I get back from a big society meeting, I am more likely to just be tired than to be excited by science. I do attend one big one per year, since it is a good idea to be seen, but I don't really miss it when I don't go for some reason. I guess there is no avoiding turning into a curmudgeon with age!