Location is #1, but let's break that complex topic down. For me:
-----1.) Warm water strongly preferred.
-----2.) Benign conditions strongly preferred.
-----3.) No plane ride over 4 hours.
-----4.) Get there in one day, back in one day, so on a 7 day trip I can get 5 to 5 1/2 days diving.
-----5.) Moderate on cost; I don't stay at hostels and forego air conditioning, but I'm not in the market for Wakatobi, either. Even live-aboard trips to the Socorros, Cocos & Galapagos have price tags I balk at. Maybe someday.
-----6.) Expected sea life is a big factor.
-----7.) If bringing family, especially 2 year old daughter, non-diving entertainments for them & good regional health care (in case daughter gets sick) are factors.
-----8.) New locations. Formerly dedicated mainly to re-diving Bonaire, I've been branching out to diversify my diving experience. So far, that's meant heading to Key Largo, Jupiter & a live-aboard (Sun Dancer 2) in Belize. Hope to add North Carolina to the list, Lord willing and providing. Interested in California someday.
My 1st 4 trips to Bonaire, I went with a group led by my 1st instructor, and had fun. Especially for trips with a lot of driving in a foreign place, and picking shore entries, starting out going with a seasoned group seems wise. For trips in the U.S. (e.g.: Key Largo, Jupiter) where traffic signs, laws & customs aren't so foreign, or for a live-aboard where they get me from & to the airport & take care of everything, I don't see much need to go with a group in the U.S. & Caribbean.
But if I were to venture farther afield, where getting there & back is longer & often more complicated (more than one connecting flight, more than one day, departure tax in local currency leaving Komodo I've read, etc...), English isn't as prevalent, and the laws & customs more overtly foreign, I'd want at least a good travel agent arranging my trip, and ideally a dive group with a seasoned 'mother hen' shepherding us around. Think land-based or live-aboard in the Philippines or Komodo, places I've never been and way outside my comfort zone.
So, some brain storming ideas for considering dive trip options for a dive shop:
1.) Who is your target audience? New Divers aiming for budget trips, such as Rainbow Reef Dive Center in Key Largo, Roatan, Buddy Dive Resort in Bonaire or Scuba Club, Cozumel maybe? Intermediate divers who've done Cozumel &/or Bonaire and want 'something different' - a live-aboard, or one of the 2nd tier destinations (in my estimation) - Curacao, Belize, etc...?
2.) Are non-diving attractions a big deal? That might put Curacao ahead of Bonaire, based on some comparison threads. Some land-based Belize trips, or perhaps a Roatan resort that offers non-scuba excursions, might work.
3.) Do you want to offer more complex trips that would be off-putting to people like me making their own arrangements? Such as group trips to do 'non-valet' live-aboard diving (e.g.: The M/V Fling out of Freeport, TX to the Flower Gardens, or one of the Truth Aquatic's boats to the Channel Islands off California)? Or to the Philippines?
Richard.