Crystal City is all hustle and bustle, but there are a few nice places to relax. This is one of them. If you like seeing trains, this is your spot. If you like seeing planes, this will work too. If you like waterparks, you're in luck. If you like oddly out of place saxophone music to complement the sound of rushing water, well then you've found nirvanna!! Even better, this should be a snake, tick, poison ivy, other vermin free experience, what more can you ask for really?
On nice weekdays, this area is crawling with people, especially around lunch time. Muggles will be the biggest challenge here. Cache should be handicap accessible. Should be a fairly easy grab whether you're walking, biking, traveling the rails (local and regional) or flying.
Congrats to Unusualsuspect for the FTF!