Those Luvees look really interesting. Have you tried them vs. plain bike shorts? If so, are these better because they are more breathable?
I really like Champion Plus Semi-Fitted Plus-Size Women's Knee Pants. They might not be as heavy as the Land's End (which is good for me because it is HOT here already), plus they have a inner drawstring so you can adjust if you change sizes. But I freaking love them as they fit me PERFECTLY, and they skim the body rather than hug it or balloon out and get in the way. Downside: no pockets.
Also, has anyone tried Junonia's QuikWik Mesh Dual Layer Short? They look awesome, but the price is kinda totally high. That being said, if they are really well made, I might consider. (Might.)