If the bookshelves can reach the spl levels at your seat, go that route. Subs take time to integrate properly and it's worth the time invested and impacts home theater as much as dialogue.
If you have the time, get a measurement mic and REW software so you can understand what going on in your room, especially below 200hz.
If you can take care of those room issues with AVRs eq or the subs, great. If not I'd look to add dsp eq at least for the subs.
Good luck and enjoy. The Ultras will be definitely be more refined for music than the Klipsch and Klipsch are probably more dynamic. Fun hobby