Looks like it has been a while since this thread was updated. I'm not as experienced a racer, or mapper, as some but here are some random thoughts:
Race is different from other modes in that it is much more linear. There is a start and a finish and what happens in between does not vary between each play through. You can introduce variety in a race map with alternate routes and types of movement required.
Regarding the traditional/classic strafe-only maps, my personal opinion is that a map is improved with a variety of options, difficulties, and types of movements (strafe, ramp jump, double and triple jumps, etc.). Sometimes this variety emerges naturally from the structure of map, other times it is very much by design.
My process is very organic. I start with an idea, area, room, or section and test it until I find it enjoyable. Then I add another area, room, or section and test the two together. Rinse and repeat. Once a start and finish are generally created, then I go back through and look for natural elements in the existing design where difficult shortcuts or easier "longcuts" can be added. It should be obvious that the shortest route should also be the most difficult, therefore rewarding skill/practice with a shorter time.
For making interesting maps, it may be useful to think of patterns in both positive and negative terms. What is the actual pattern that exists and what are the patterns that do not exist? In a way, it is like music with on-beat and off-beat. If you repeat the same situation in a race map, over and over again, it can become boring. Instead, finding ways to break patterns by introducing something unexpected may be a useful way to think about it.
Pat Howard wrote a very interesting article on architectural "connectivity". Although the article is intended as for duel/TDM food for thought, I think the same lines of thinking can be applied to race maps. How do various sections of your race map connect together? Do you put some trick jump between two areas or in the middle of the rooms? Consider all the movement mechanics and possibilities and all the potential combinations thereof. What patterns can you arrange with all these possibilities and how can you interrupt/break these patterns in interesting ways?