We have a 22 ssbxp and love the swing back configuration, though how you will use the boat will dictate what you need as a layout. If you go with a swing back, get the keeper rail. It is worth it as it makes it usable while underway.
One of the best decisions that we made was to get the center toon storage. We use it all of the time and it opens up the under seat storage for guests in a big way, and keeps stuff from getting underfoot on the deck.
We have SPS with a Yamaha 150 and it moves and handles very well. The engine is powerful while also being quiet. We have a standards tow bar and use it all of the time. That said, no one ever complained about having too much horsepower. If you want more, get more but be aware that there are minimum requirements on the hull (ESP vs SPS) and size of the boat. The 22 foot that I needed due to the size of my dock, the waters, etc matches very well with the 150 and SPS. You should test drive once you know what length you want to decide, if possible.
The SS series includes a lot of options. Our budget allowed for a "higher" trim level, but I think that Bennington provides a sold product in every trim line. Our trim cam with extended decks, and I wouldn't do without them. We didn't get an elevated helm, and that is one option that I probably would add if I ordered it again. Not a huge deal, but nice to have.
We got the changing room option and have not used it yet. It is out of the way in the swing back configuration so not a big deal on space, especially with the center toon storage.