Advice for first pair of Maggies

You might want to post some details on your music room. You will do well to select a model that fits the room well. As far as buying used, the older models have had problems with the glue failing after varying amounts of time. Direct sunlight and humidity extremes apparently speeded up the glue failure. I had a pair of SMGa's that did this. You will hear a nasty buzzing and you will know something is wrong right away. I've had a pair of 1.6QR's for 12 years and they have no problems at all. For today's going prices for used 1.6's, they are an insanely good buy. If I were buying maggies, I'd try to pick up a pair within driving distance and go see and hear them. Most people would rather not ship them, so that should work for both parties.

The glue issues in current or recently built Maggies is not longer true. Magnepan has changed the glue they use and the story is the newer modles will not come loose like older ones did.
The glue coming apart IS the issue for old Maggies.
It is a pretty easy fix to do, and if you look at the Planar asylum over on Audio Asylum, you can read about folks regluingthier Maggies.
I own new last Spring Magnepan 3.6s.
I almost was able to buy some used locally, but they and my money did not co-incide. So new it was. ((As shipping used Maggies is a bigger problem than most speakers, just 'cuz of thier shape).))
Maggies are a love them or hate them sort of speaker. I personally love them. They are probably my last pair of speakers.

Elizabeth is correct about the glue issue. Only the earliest Maggies had this problem. Magnepan corrected the problem in the early to mid 80's.

Room size is something to consider when selecting a speaker and Maggies sound better in a medium to large room.

My room is a rectangle, I think it's about 10'x15' but I'll have to measure to be sure. I am planning on putting the speakers on the short wall and will be able to place them 7'+ apart. There is a window in the middle of that wall. I will be able to bring the speakers 3' off the back wall, I don't know if I can do much more than that.

Are any other details needed to determine if the room will be a good fit? Thanks for your help!

That set up should work well. I've used an MMG Hibachi system in a slightly larger space with great success. Adding a sub later (maggies and subs DO mate well, if you use the right tools) will create a wonderful full range system. Your specific choices (MMG and Hibachi) are IMHO the first steps in a "crazy value" full range system

Good luck

Marty