You're welcome

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I totally get the excitement about checking into the Poly as your first resort

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Yes, for a split stay, doing a package with the first resort and RO for the second is probably the most economical. Getting the
DDP for both resorts adds cost as the DDP requires a minimum purchase of a 1 day base ticket for everyone in the room (2 day base for FD), so it does make sense to get park tickets for the whole trip on the Poly reservation and book RO and pay OOP for your meals for your Epcot resort reservation

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LOL about being brave going in July

. This will be our second time for a July trip. On our first July trip (2002), it was hot, but we spent a lot of time at the resort swimming and went to BB a couple of times, so it wasn't bad. Next year my brother and SIL are going with us (taking my niece for the first time) and since my SIL is a teacher, summer works better for them. When my brother mentioned he wanted to stay at the Poly I was ecstatic as the Poly is our favorite resort....plus the pool should be open by July and the GCH and Captain Cooks should be done. I'm sure there will still be DVC construction going on, but that won't bother us...as long as we have the main pool and everything else is done, we're good with it

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Unfortunately, Disney doesn't usually offer deep discounts for a resort that is undergoing construction. As the pp mentioned, a room discount was being offered, but that has expired.