Wvrick. Don't know specifics where you plan to vacation dive but in my experience you won't have any trouble finding a dive "buddy" on the drift dives out of WPB, Florida or areas nearby. The boats I go out on often have single divers that pair up or just drift along with the DM. Kind of depends on your skills and comfort level. The boats also often have "regulars" on board that don't mind helping out a fellow diver.
In Bonaire, there are so many divers that there too I couldn't imagine it being a problem. There are several threads on SB discussing travel to Bonaire as a single diver and ways to find buddies including bulletin boards at the resorts. I recall one flight to Bonaire where a diver announced he was looking for a buddy. When we saw him later on the island, he had already found one and together rented a truck and completed several dives.
We will be in WPB in one week looking for lobsters if interested...