GP is at the junction of International Drive South and Osceola Parkway. OP is the highway which runs east to west along the bottom of WDW property (more or less parallel with the US 192). Major landmarks are AKL and AK to the far west, and Pop Century and the Wide World of Sports towards the eastern edge. After leaving WDW property travelling east, you cross the I-4 and Gaylord Palms is then quickly visible on the right. You can't miss it - it's huge!
If you are travelling south along I-Drive, it's a little trickier. There's a 'chink' in International Drive South at the major intersection with the 536. You need to take a left at the lights onto the 536 (it's an odd junction - you almost turn back on yourself), then very shortly afterwards (a couple of hundred yards or so), you need to take a right back onto International Drive South. It's very easy to miss.