Right now, travel is not important to me at all, and we follow the opportunistic route. We don't budget to travel, but when we do it it's inexpensive enough to pay for from side income, etc.
I have traveled a great deal in my life, and it got to the point that I was sick of it. Travel has slowed down a lot in the last few years, since I started a job that doesn't require as much and we have a young child. Since having a break, I'm less sick of it, but still not itching to travel.
Currently, we take one or two trips a year driving 5-9 hrs to visit family. Other than that, we've take a few trips with my parents, including a cruise to Bermuda last summer and will be going to a beach with them this summer. But, for those trips they helped to pay for costs (eg., renting the condos we're staying in this summer), so they've been inexpensive.
I'm thinking that maybe next year, DD will be old enough and I'll be enough over being sick of travel that I may try to take a work trip to somewhere interesting and bring DH and DD along (so we'll only have to pay for their flights, their food, and some entertainment).
As of now, I'm not figuring large travel costs into FI. Maybe my perspective will change again over time, but as of now I'm thinking that I might want to take one bigger trip to somewhere really interesting every 2-5 years if I'm really interested in going, and otherwise just do the type of occasional small opportunistic traveling we've been doing.