To make your marriage proposal memorable, I can also suggest you my website, where 30 romantic ideas to pop the question in Paris, France, are available.
Nicolas, Founder of http://www.proposeinparis.com
A big part of popping the question is the style of how it's done. None of that "Well, we might as well get married, I guess" kind of stuff.
The thing about El Encanto is that it's centered on a beautiful lake, bobbing with graceful ducks and geese. While we're getting fed truly delicious Sonoran food (viva la margarita!), the waterfowl are hoping we'll spring a quarter into one of the grain-filled gumball machines. Turn the knob, fill a little paper cup with delicious goose chow, and the birds come flapping over.
Now here's our idea: Put the quarter in the machine. Fill the cup with grain. Then, take that expensive rock and stick it down into the bird seed. Hand the cup to your sweetie. Just be sure she doesn't toss the whole kit and caboodle in the pond. Isn't that romantic?