JD,
My Redhead is a plant maniac, as was her mother, raving plant lunatics, both of em.
Here's a pic of our humble little place when we bought it, near 5 years ago & a few shots of this Spring. There was nothing here but a couple sickly Rhodendrons, weeds & rocks. We scored a sweet deal the 1st year we were here, a friend with an extensive mature landscape called & offered to split some of her things, we came home with a pickup full to capacity of plant starts & rootballs. Took a couple weeks to get it all planted.
Local nurseries, real nurseries as opposed to Home Despot, have experienced staff, usually more than happy to offer qualified advice.
The good Capn Juan has the right idea with relatively low maintenance plantings, concept doesn't work so well when you have a partner that's crazy. We try to choose a good percentage of plants that give more than one show, pretty blooms in the Spring & Summer & flashy Fall color, or evergreens
You're doing this at just about the worst times to plant, hotter than blazes & dry. You'll have better success with less effort planting in the Fall, particlarly with trees & the expensive exotics your Mrs is bound to find.
The first planting season here I hauled in 3 yards of chicken manure & 6 or 8 yards of mushroom compost from the farm up the road . Stinky stuff & hot, I got a little carried away with the chickn poo & we lost a few things because the ground was too hot, not bad, survival rate 90% + & thriving.
Ornamental grasses are a pretty safe bet, they come on quickly & are usually pretty tough. Later, as your more exotic plantings mature you can remove the grasses or transplant them elsewhere.
http://www.naturehills.com/catalog/Pere ... Grass.aspx
I'm not sure what's in this product but it works, makes a substantial difference in the survival rate & how fast the plants come on. A little pricey but a pint goes a long way.
http://en.wikipedia.org/wiki/SUPERthrive