For out-of-state travel from the Houlton region the only real alternatives are in Presque Isle which is an hours drive North (50 miles), or Bangor International which is 115 miles South. Quite frankly after living in the Presque Isle area for close to 20 years I always drove down to Bangor for flights because I could save money by driving the distance over airfare. Monticello is a wide spot in the road. Quite literally a wide spot in the road, If I recall correctly it has 4 or 5 side streets (2 East/West and 3 North/South), I don't remember if the Gas station was still open when I drove through last month.
In all reality, while Houlton IS the county seat for Aroostook County, there isn't much going on there. Presque Isle has been the one attracting business/people the last few years, but that has slowed somewhat right now as well. The communities surrounding Presque Isle is where I would be looking if I were moving to Aroostook County. Fort Fairfield in particular. Expect cold, last winter was a bit warmer than usual for us in that area but lots more snowfall than usual. We had 44 days below 0 for the low temp, and only 2 or 3 below 0 for the daily high temp; plus 197.8" of snow in the Caribou/Presque Isle area. Usual is around 50 days below 0 for the low and 8-10 days below 0 for the daily high; snowfall is average 110" up there. Snow WILL be on the ground in November and will stay there until April on average, some years more, few years less.
You
WILL freeze the first winter! Know that now, before it comes as a shock. The first winter you will swear you lost your mind for moving to the inside of a freezer (actually, household freezers don't get as cold

) . The next winter will be much nicer to your system. Coming from the South can be a harsh adjustment period at first, but the Summers make up for it, I promise.