Not planning a Galaxy class at this time. Far too big, and there are numerous fine deck-plans already out there (including semi-official ones, such as the set I have on my bookcase). Excelsior, OTOH, I envision much the way the art designers originally did: A larger, newer "Enterprise replacement" (the role it filled in ST-III). As such, I envision not much more ROLE than we saw Enterprise performing, but far more capable over the long haul. Having poured over Enterprise in this detail, I can tell you she is a bit of a cramped ship for 430 or so crew. Junior crewmen (All enlisted and Junior officers) HAVE to share rooms - if not even hot-bunk. There's just not enough space to fit everybody otherwise. R&R facilities are limited to the Rec Dec, the gym, botanical garden, and a small swimming pool. In short, think closer to Attack Sub than Missile Sub or Surface Ship for space. For a designed 5-year (60-month) cruise (assumption, I know) you of course include more amenities than you would for a 6-18 month cruise design (think some of the smaller FASA creations, such as a Locknar). Excelsiors would be designed to be much longer-legged - more amenities, better facilities, moderately larger crew requirement. It would permit them to operate well into the TNG era as viable ships long after the older Connies were retired from service.