During the spring and summer here in Houston hot weather gear is the norm. What I wear specifically often boils down to where I'm going. If I'm going to my day job at one of the local universities where I have shower and changing facilities available due to the distance involved I prefer to wear loose mountain bike shorts and a conventional coolmax cycling shirt so I don't look so conspicuous . Very early in the season when it's still cold and if I can get to work without sweating I'll wear my Lycra road bike shorts and a white coolmax cycling shirt which saves some time as I skip the post ride ablutions and just pull my work clothes on over my cycling clothes. I also use this method through the Spring and summer with my weekend job were I'm there less than 8 hours and there isn't much time for changing at quitting time.
I would have to say that 95% of the time I prefer the baggy shorts approach as it seems motorists cut me a bigger break when I don't look like professional bike racer. Along with this approach I tend to stay away from the neon, wild graphics, "I am a Bicyclist" cycling shirts. Most of my shirts are basic colors such as red and white. The white shirts like I mentioned before can double as a t-shirt while at your work site. They are also most useful for visibility reasons for early morning before-the-sun-rises commutes. I have tried "road hazard" colored shirts I have a neon yellow and a blaze orange colored shirt; however, the only time I wore the blaze orange I had a Village Cop(ulator) pull up and harass me at 5:30 am about not using the Village bike lane/sidewalk (Sun wasn't even up and he and I were the only traffic) then passing through Memorial park I had another meathead drive next to me at tell me to use the sidewalk (at this point of Memorial Drive passing through Memorial Park there are no sidewalks of any kind until well past the park, a distance of two miles. ) As for the neon yellow I haven't tried it yet as I fear a worse reaction... Blaze Orange seems to make motorists and policemen combative I'm afraid neon yellow will push someone over the edge and make me a hood ornament.
Also, as far as lycra shorts go.. basic black is the most appropriate color on a man. Definitely no gold or white. The former might give some people Rocky Horror flashbacks and the latter is just disgusting.. No one want to see your pink hairy A$$ crack sucking a bicycle seat from under sheer white material. Note these rules don't apply to women as most I've seen could pull off the different multicolor/light colored shorts without looking in some way disturbing.
As for construction you can go wrong with the classic leather chamois; however, you have to concide that there are better materials now available like the coolmax chamois. I'm partial to this new chamois; however, only if it's sewn in right and if it's the right size for the shorts. I have a pair of Performance shorts where it has the coolmax chamois, but it's short (and the shorts are actualy a size larger thant I normally wear) and the foam rubber is exposed which has a tendency to grab hair and skin and cause irratation. By far the best implemetation has been my Pearl Izumi shorts that I picked up at Sun and Ski Sports
As for Mountain Bike shorts for commuting I prefer lighter colors for visibility. Most of my light colored shorts are Tan/Khaki . By far my favorite mountian bike shorts are Zoics.
Here is a pic of me from an average commuting day.