See, now that lot is perfect for an ambitious mixed-use project of 30 stories or more (and maybe some adventurous architecture). I'd really be disappointed with anything shorter than 40 floors. Retail on ground, perhaps service-oriented (coughgrocerycough) as it would be in easy walking distance of 110, Avalon, Waterplace, Capitol Cove, the RISD students dormed in 15 West, and hopefully its own residential units, not to mention that its proximity to the train station might prove valuable to commuters; a good deal of parking would complete the base of the tower; and then in the tower proper, maybe 10 or 15 stories of offices; on top of that, a floor containing a separate entrance for the residential units in the upper tower and perhaps a couple of spa or gym type amenities for residents only; and finally, starting no lower than the 15th floor, condo residences, which would have utterly spectacular views (over the 13-story Citizens building) down the Providence River and out into the bay, of the East Side, of the statehouse and its estate, of Waterplace Park, of the Financial District and the skyline, of RW National Memorial and Kennedy Plaza and City Hall, the works.
All of this would be pedestrian-oriented and would, of course, incorporate seamlessly with Waterplace Park.
Don't rain on my parade. A boy can dream.