Any of them will look good their first year or two in the ground. And then things will start to go wrong - brown rot, bacterial canker, graft failure, shothole fungus, gummosis, winter cold damage (which seems to have wiped out a fair number in the last couple of winters), etc, etc. Just make sure she understands this is unlikely to be a very long term addition to her landscape.

In my area (Z7 MD), there are a lot of the high grafted weeping cherries that never get more than 15 feet tall in the newer subdivisions but at the same time, there are some massive specimens that can take up a whole yard. That being said, I have no clue what variety they are but there are some more long lived (relatively) weeping cherries out there.

I am aware that they are disease prone.....but was hoping someone could point out a couple good cultivars

There aren't all that many - for pinks you are looking at Prunus x subhirtella 'Pendula' (sometimes will have 'Rosea' tacked on to the labeling as well), either as a tall growing tree or grafted as a shorter standard. Or for double flowers, P. x subhirtella 'Pendula Flora Plena' or 'Yae-shidare-higan' (not sure how distinctly different these two cultivars are). There are a couple of others as well as a few white flowering forms but these are the ones most commonly offered and planted.

viper - Gardengal's suggestions are lovely, elegant trees and I would buy them like a shot if I had space. But be aware they are winter and early spring flowerers in milder climates and the blooms are not large, so they might not be the blowsy ballet tutus you are thinking of when you have 'flowering cherry' in your mind's eye. Research all suggestions thoroughly so you know what you are getting.

In later years weeping forms of Higan cherry have tended to be placed under Prunus pendula (rather than P. x subhirtella), with more distinct ones such as 'Pendula Plena Rosea' (double weeping) and 'Pendula Rubra' (darker pink, with leaves indicating this one may actually be of hybrid origin) having such cultivar names in the West. Japanese sources (and Western authors following them) use Japanese names instead, for the same plants.

These growers have a couple (scroll down to Prunus) they claim resist shot hole at least. Don't know current retail presence. Have noticed the unfortunately named [Pink Snow Showers] = 'Pisnshzam' making an appearance on the local market, not sure it took hold however - but some places have cut back so much on trees in the current buying climate it is hard to tell if a particular kind not being presented repeatedly means anything or not.

http://www.lakecountynursery.com/lcns-view-selections.html