We have had a vented gas fireplace, unvented gas heater, and a vented gas Franklin stove. The Franlkin stove gave off the most heat. The heat radiates from all 4 sides of the stove and stays warm for over 15" after the gas is off. The heater was hot at the time, but the heat just rolled forward and not at all like the Franklin-style. The fireplace gives off little real heat quickly, but after several hours the room heats up a little. This is just from our experiences. We are adding a sunroom and hope to go with the vented Franklin if we can afford it.

IMO, go direct vent. The top vent (regular chimney) is just that, a regular chimney pipe - a single pipe carrying combustion products out of the home. When using a regular chimney, the combustion air comes from somewhere else, usually leaky windows, doors, bathroom fans etc. To me that means you lose comfort (it's drafty) in those areas where you're pulling combustion air into the home. And the pipe gets hot so you have to respect the proper firecode installation rules. On the other hand, direct vent chimneys are double-wall pipe. The center pipe carries the hot combustion products out of the home and the surrounding outer pipe brings in the outside air. That cuts down on the drafts at doors and windows, plus the outside of the vent pipe runs cooler, so it should be safer from a fire standpoint (you still install it per the firecode). The safety of direct vent IMO would be higher. I don't think there would be any major difference between installation, cost, appearance of the fireplace, or flexibility between the two options.

All the dealers around carry Peterson RealFyre - but this forum has several negative posts about them. I want to find some "realistic" looking 24" gas logs for my vented fireplace (we've been burning wood in it for the time being) that don't put off much heat (we're in Florida in a new home). I can't find the BTU detail on the Rasmussen logs - but maybe BTUs don't tell the whole story? How can I determine which logs are going to fit my needs?

"...the Northern region...." and "..cold winters...." are not very specific. To people in Florida, Virginia has cold winters. Additional information about climate and your gas and electric rates would be useful in advising you.