We have planned almost every one of our trips a few months out (also waited for discounts): I think our record was one month for a trip in April '07. Our most recent trip we booked five months in advance (mid-January for an early May trip), which was, of course, a month shy of making that 180 window. We ate at some off times, but got everything we wanted: Chef Mickey's, Akershus, Via Napoli, Kona, Ohana Breakfast, Sci-Fi, and Garden Grill. We didn't go for BOG, CRT, or CP, and while we had a late dinner at Chef Mickey's and an early dinner at Sci-Fi, we were happy with everything we got (we even changed Via Napoli from Friday to Saturday while we were there and were fine). We booked before the FP+ window, so that wasn't a problem at all. Often ADRs become available closer as people fine-tune their plans or drop things, so there's always hope!
I think the main thing is flexibility. Knowing that you won't have the "perfect" ADR ahead of time really takes some of the stress away. When we book in that way and know we probably can't pick up pre-opening ADRs, we book ours at the very end of the window for a brunch so we still get the morning in the park. I am in the firm belief that you could plan a trip the week before and still have an amazing time. There's way more things that you can do than can't do by planning a bit later than some. So a few months ahead is still enough for an amazing trip!