How smart of you to do all this
before you get married... hehehehe....
I've heard a lot of good things about the ADA line of substrates over at aquaticplantcentral.com, and those guys know their stuff, so you can be assured this is a high quality product.
What filter are you getting btw? If you can afford it, I'd recommend the Eheim range of filters. Easy to diffuse CO2 with it as well. But since you're going pressurized, I think using a diffuser would be a better idea.
If you're really serious into planted tanks, I'd recommend you register at the forums at aquaticplantcentral.com, as they have some friendly hobbyists over there who are more than willing to help you out over the way... Specific forums for aquascaping, substrate, ferts, lighting and many more, with top name hobbyists such as Jeffrey Senske and Tom Barr posting there regularly....
And no, I don't work for APC...
Cheers,