Running World list the DisneyWorld Marathon as one of the better 1st Marathons to do because of the great fan support and flat course.  I've run a half there and have to agree that it has plenty of support at every mile and you can't be runnng through the different parks. I am looking at doing my first marathon at the Space Coast Marathon in Cocoa, Fl.   I ran the half there this past year and it is beautiful.  Like you I have been running a few half marathons, in fact I will be running 3 half marathons in 4 weeks. My thought is that my training runs have already gotten up to double digit miles at least once a week so it isn't that much of a stretch to do it. By the fall I should be able to do a few 17 - 20 mile runs.

1.5 to 2 months is actually my favorite time to fit in a pre-marathon half marathon race. It gives me a chance to pick up my pace for a longer distance, while still having enough recovery time afterwards and still a few weeks to get in some long marathon-training runs. You should be fine.