Where are you located Yankeewinemaker?
Let me be clear about something here- unless you are planning to make a lot of wine, a half acre is way more than needed for a home winemaker! In their third year with less than 1/2 acre in production, I got 4000 pounds of grapes this year in the Champlain Valley. That is enough for 250-300 gallons of wine. They aren't even in full production yet! I will have three times the grpaes producing in this coming year.
With that said and out of the way, all those varieties are good ones for NY. The possible exception would be LaCrescent. Why? Because they tend to frop grapes off the cluster before totally ripe here in the northeast for some reason. This is from personnal experience at the test vineyard in Willsboro and from other growers here in the Northeast. With that said, the flavor and versatility of the grape make some yield loss tolerable.
Frontenac is a high acid grape and has cherry flavors. It is hard to get ripe enough here to be without the acid problems. In my opinion, Sabrevois or St. Croix are better choices and give better wines with less problems ripening.
Marrquette. With one year's experience vinting it, I and other tasters are less than impressed with it. It does grow well and I havested enough good ripe grapes at 27 brix at Willboro to send to the Cornell lab for vinting. We will get results later this year.
Frontenac Gris- I have a batch going right now that I will be running through MLF. Initial tastes are great, but not quite as good as the LaCrescent. I had a bottle of 2007 mixed LaCrescent and Petite Amie-50/50 that was OUTSTANDING. Very fruity, great acid/sugar balance, excellent mouthfeel, etc. Petite Amie is now available at Double A Vineyards in NY.
Let me know where you are located (PM me if you don't wish to disclose that here) and we might be able to arrange a sampling. I have all those varieties andmore from 2007 except the Frontenac Gris, and that one is now clearing so it could be sampled in the future.
And Dont' Listen to Northern Winos- NW about me being the answer man, I just have a bit more experience in growing these things. I'm learning like all the rest of us!