NickB,
that was our EXACT itinerary and you will be amazed at the service on the Avianca Business Class flight!! However, u will sweat all the extra calories off when u arrive in Bogota.
We were also worried about the tight connections, but had no problems what so ever. The Aviateca flight was actually held a few minutes for connecting passengers when our Bogota flight was delayed. You will be checked in for all your TACA flights in Bogota. They will also take all 3 of your TACA flight coupons.
I would strongly recommend the "All-Suite" Radisson in Guatemala. We were able to obtain a 65USD rate using a web saver. The taxi from the airport was 7USD and we took a free airport shuttle from the hotel back to the airport. There are some great places to eat right outside the hotel.
In reference to the Copa to Taca connection in MGA. I would strongly recommend you get the boarding passes at the GUA Taca desk. However that said, I am pretty pleased we got bumped. Sue and I were not scheduled to return to DC until Monday, so rather than sleeping at the Miami Airport Farfield Inn, we got to spend an extra day in MGA at a top notch hotel with all meals paid. The upgrade to business was a bonus.
Good Luck and have fun,
rich