Try one first...I've been camping with some folks who have one and was pretty underwhelmed, especially given the propane used. Not sure what counts as "decent warmth" for you, but I thought there were mainly psychological. But that might be enough; the light and something to gather round are often what people want most. More on reddit.com

I can get propane for $12/tank (20 lb) about 2 miles up the road, but nothing beats a wood fire pit. More on reddit.com

Depends what you want to spend .. there's a lot of specialty shops in florida for outdoor furniture but to keep it simple, get an aluminum one. Most all should be aluminum now... but you never really know how pure it is unless you pay a little more at a place with a warranty. Concrete is another option. .. but make sure its actually like a polished concrete and not GRC - glass reinforced concrete - or MGO - magnesium oxide. Those with fall apart with salt air in the south and freezes up north. I was an outdoor furniture desinger for a while and Costco pretty much had the best price to quality ratio. Cast aluminum is the way to go for florida winds and salty air. More on reddit.com

If it's gas you'll turn it on a surprising amount. Not the same thing but I had a wood fireplace I only used maybe 2-3 times per year because I was never going to sit down long enough to justify starting and tending the fire. I replaced it with an electric unit, I use that every day because I can turn it on for 20 minutes and turn it back off again. More on reddit.com