I love my Latitude jacket and pants and I live in the same part of the country as you and ride similar missions.
I didn't do an exhaustive comparison between the Klim offerings.... basically, the Latitude meet my criteria for a Gore-Tex do-it-all suit and was just at my threshold of pain for cost (about $1K all up). I didn't consider spending more. It was between the Latitude and a new Aerostich 2-piece Roadcrafter and I decided to get something a little more stylish and tailored this time around.
From what I've read, none of the Klim gear, especially the bulkier high-end adventure-oriented stuff, fits very well over street clothes. And the Latitude pants have a little bit of an odd fit - they're roomy overall, but the waist is cut in fairly aggressively and I think you'd have to go way-too-big in size to have a waist that would allow another pair of pants to be comfortable underneath. But with my typical over-the-road kit (silk-weight long johns), they're very comfy. I think Klim specifically says the pants are NOT cut for them to be used as overpants.
If you want the ability to go over clothes, I think it is hard to beat the Aerostich Roadcrafter, especially if you go the 2-piece route and use the bibs accessory to hold up the pants. This gets you a lot of room underneath. For street touring, I'm still going to be using mine.
BTW, I'm getting ready to depart on a big tour which will involve cold weather riding AND desert riding and I'm packing some mesh pants as well as my Latitude. I just can't see this stuff breathing well enough to be anything but super uncomfortable on a 90+ deg day. I think the Roadcrafter has bigger vents and more flexibility in this regard.
- Mark