I have made only three mods to my XT250, and they all add to the same advantage, getting me to new places.
1) I replaced the sh*t seat with a Seat Concepts. Before I got a sore butt within a half hour, now I can cruise for half a day without even thinking about taking a break. I don't understand Yamaha's reasoning here, the two seats are basically the same materials and construction, just having slightly different shapes. Yamaha could have done this for no cost.
2) A rear rack and top box. I can carry supplies to enable me to travel further.
3) A cheap GPS. Now I can go with confidence to new places, that I wouldn't have attempted before.