Welcome,
@LaurenNYC! Upstate New Yorker here.
I think you've chosen wisely.
FWIW, we ("we" being me, DH, and our then 9-year-old daughter and 11-year-old son) did a split stay in early May 2018 (3 nights at Beach Club, followed by 2 nights at the Polynesian, both in standard studios on rented DVC points -- it worked out to $250/night at BC and $410/night at Poly).
The Poly stay was one we'd fantasized about for years, and we split it with BC largely due to the high cost. It was everything I'd dreamed it would be. We loved the retro Tiki decor, and the extra-large studios and extra bathroom space (especially the deluxe shower) were fabulous. We had plenty of space in the studio to use all the sleeping spaces, and still step easily around the room and access items stored in drawers. We spent a couple of glorious mornings sipping coffee on our large balcony, which overlooked some lush greenery and a quiet walking path. The convenience of monorail transportation (and a short walk to the TTC) was cool, too.
In comparison, we were really disappointed with the Beach Club. Our studio balcony was filthy and faced a noisy roadway -- not that we could have accessed it anyway, because the BC studios are so tiny and crammed full of oversized furniture that with the sofa bed folded out, we couldn't get to the sliding balcony door. In fact, the BC studios are so small that with the Murphy bed and sofa bed folded down and the chairs, sofa cushions and coffee table occupying the rest of the floor space in the bed room, crossing the room was like an awkward game of "The Floor is Lava," because you had to crawl across or straddle all the furniture to get around. Plus, with the sleeping spaces folded out, you couldn't use the table (it folds into the Murphy bed, whereas the Poly has a separate table and chairs), nor could you open or access any of the storage drawers in the Murphy bed unit or coffee table. We ended up having to perch on our beds to eat breakfast, and store all of our clothes in and around the bathroom vanity, or inside our suitcases in the narrow entryway. Counter service dining at BC was limited and boring except for Hurricane Hanna's (in contrast to the Polynesian, which had more interesting options), and while we'd heard rave reviews about Stormalong Bay, it was a nightmare to be there with active kids. You're fenced in like a criminal (all the pools have fences now, but the one at Stormalong Bay is particularly visually intrusive and totally interrupts the flow of the area), the pool slides are across a busy walkway in a completely different fenced section, and there are so many different levels and visual obstructions that we were constantly losing sight of our children. It was the opposite of relaxing! Granted, the ability to walk to Epcot and HS was nice, but I didn't feel it made up for a room layout and resort pool complex that seemed singularly ill-designed for a typical family.
At the Polynesian, the pool was beautiful to look at, and we could see the whole thing from any lounge chair, so we could easily keep track of what our kids were up to, instead of having to chase them around. It may have been less elaborate and there was no lazy river or anything, but that was okay with us -- there are water parks for that!
Overall, despite its higher price, I'd stay at the Polynesian (for a couple of nights, anyway, whatever we could afford) again in a heartbeat. I'd never care to stay at the Beach Club again, even at the much-lower nightly rate. That's my 2 cents.