For what it's worth... it sounds like your dishwasher is broken if it has standing water in the bottom of it. Ours began doing that a few months ago, and was not cleaning the dishes and was leaving a film of nasty stuff on there. We had an appliance repair man come out, and he found a little plastic gizmo had broken - it was the piece that was supposed to grind the little bits of food so they could go down the drain. Well, with that little thing broken, the drain got clogged and that meant that the dishes were being rinsed with water that had food particles in it - hence dishes that had a film of gunk, and the standing water. The little part was about $5, and his time was $75, and our dishwasher works great now! Before you go and buy all new (unless it's a really old dishwasher to begin with), why not just have yours checked out? You would save a few hundred dollars and it could resolve your problem completely. Just a thought!
If you do have hard water, use a rinse aid like Jet Dry. We have very hard water here, and Jet Dry keeps the dishes looking nice. (Changing to a new dishwasher will not have an effect on the hard water, though. You have to treat the water.)