^Yeah, I'm just throwing ideas out there. Well, NY 275 is another short-ish connector you could do (Friendship to Bolivar). In Wyoming County, there's the incredibly short NY 362, with a one-lane section I believe was originally a railroad underpass. And don't forget NY 248 and NY 248A, which can also be used to get Potter County as I stated in another thread. All this will probably end up taking multiple trips.
I see on Travel Mapping you have gotten NY 39 down to NY 436 past Castile. A great longer road to finish up would be NY 39. It's quite a scenic road, I know this from experience as I've been on all of it except for the part north of Geneseo. As you head west you will see beautiful rolling hills and farmlands throughout Wyoming and Livingston Counties, then go through the neat village of Springville in Erie County. Later on, after traversing more hills in the Zoar Valley region, you will approach Gowanda, an interesting little village spanning two counties. From there you ascend out of the creek valley and see northwestern Cattaraugus County. As you reach Chautauqua County, you will descend a long hill into Forestville, a tiny village with a weird median setup. Climbing out of the village you will start to see some vineyards, before ending at US 20.
While you're in Chautauqua County, you may as well check out the county touring routes. They are kept to quite a high state of quality, about as good as a New York State Route. They are numerous and extensively cover the county, and you might get some really neat views, such as when I once saw the Buffalo skyline from CR 93.