Just back - here is the run down about how it went. We had the same experience with the stop in la Ceiba. However, we did not retrieve our bags - they were "checked" through to SAP. (Sort of like a gate check in the states). We arrived in SAP by 8:15. However, the continental desk did not open until 9. We were near the front of the line, so were checked in by 9:15. We did not need to be back until 11:45, even being cautious, so decided to go into town. Here is the key part: our resort arranged a hired driver, so it made things efficient and predictable. It was $30 to town round trip for both of us. We left about 9:30, got to the market by 10:00. We left there a bit before 11:00, stopped by Central Park for a few pictures and an espresso, and were back at the airport by 11:30. The line to pay the tax was quite long, but it moved really quickly. The line for security was fairly short and we had no trouble getting through. We were at our gate by 11:45, and then of course had to wait.
The city of San Pedro Sula is not great for sight seeing, but I am really glad we went. It is impoverished, and typical of the area, crowded, dirty and industrial. The park was lovely, and surprisingly clean. The market is stall after stall of crafts, and an area of flowers and produce. There weren't really gifts/crafts on Utila, so was good shopping. Coca Cola sign in the hills is a hoot.
Bottom line, we are pretty brave travelers, so were comfortable being away from the airport. If you don't have an arranged driver, I would be less comfortable. Ours didn't speak english, but waited for us at each stop, and minded our bags, so we knew we could get back quickly. Ask at your resort.
Note: there was NO RUM in duty free shop (except bacardi, ha ha), so if you want to bring some CA rum home, buy it on the bay islands, put it in plastic in your checked bag and cross your fingers!