Boating and alternative energy sites may have useful information for you. There's a pretty good chapter in Nigel Calder's book about boating.
Lead acid is probably cheapest, and you're hams :-) If you don't have time/interest/manpower/venting you want sealed batteries, probably AGM rather than gel cell.
You'll want to quantify along the following axes:
o How many charge/discharge cycles of lifetime?
o How deep will the discharges be?
o What will the peak currents be?
o What will the average currents be?
o Is the environment temperature controlled?
One rule of thumb is that you should size the battery pack so that it only gets down to 50% or so of capacity at most. Past that, the lifetime starts shortening dramatically.
Another rule of thumb is that you don't want to pull current out of the pack at more than ~10-20% of capacity per hour. That's only a guideline and the numbers are different for different battery designs.
Golf cart and forklift batteries are impressively durable but usually not sealed, so you have to think about battery acid and hydrogen when you install them, and you'll have to add water periodically.
Cheap chargers can do permanent damage to batteries -- look for a good charge controller. If you have temperature swings, look for one that varies its output voltage depending on the reading of a thermometer at the battery installation.
Is this the kind of info you were looking for?
Fred KC7YRN