You mention turning it into a "family vacation", so I assume that you intend to include all the kids of the adults you are inviting to the wedding festivities?
If so, great...but if not, then you put 'families' in a bind because they have to figure out what to do with their kids whether they bring them or leave them home.
And I'm sorry, but taking a family to Disney DOES cost thousands. It can be done inexpensively, but its still a significant expenditure in terms of time and money.
You mention that they would be coming to Florida anyway since you live there...I don't mean to sound pessimistic but are you sure all would travel? If so, perhaps they would have stayed in less expensive accommodations (renting a house, perhaps, and splitting that cost?) or only stayed for a weekend.
Anytime to are asking folks to lay out ANY amount of hard earned money and vacation time you need to adjust your expectations. It doesn't mean you can't and shouldn't do what YOU want, but you have to realize that not everyone can reasonably participate.
generally, i agree. and noone should take offense per se at someone not being able to come, and noone knows whats really going on in anyones' wallets!!!
that said, i don't think the idea in some folks' minds about what something along these lines might cost is always reflective of what it does cost. for us, we have invited only the closest family members and then given TONS of notice so that appropriate plans could be made - get that vacation time off, get the best deal on airfare possible, etc...
so really, again, all you can do is provide info and answer questions and let the chips fall where they may...
as to the kid issue - as long as kids are included in the wedding itself - mentioning a "family vacation time" is just another idea for guests to think about, not a commitment to host the guests for the week!
its always a tough one! my cousin'd 2 sons got married within 6 months of each other and initially both stated they wanted destination weddings in the carribean, that of course mom and dad would be paying for. my cousin told them both if that is what you want to do, we can pitch in x amount of dollars, but we can't afford to come in addition to that!
also side note, everyone i am related to who lives east of the rockies seems to think driving 22 hours in a mini-van full of people is part of the vacation so maybe folks will want to drive! we ourselves are only staying on property (me) the night before the wedding and on our wedding night, because we are renting a condo (that we are paying for) to hold us, his 17 yo son, his mom, my step mom and my borther and his wife. we certainly couldn't afford to stay on property for 6 days and host all the wedding stuff and eat! that full kitchen is going to be our lifesaver!!!