Friday Swim Workout

Alright, so I made it to the pool today to start doing some sprints. My last speed-related workout is posted below somewhere and included timed sets of 500 meters (not really sprinting, i know). Today's workouts and results are as follows:

Wilson Aquatic Center

Workout - 2000 meters
500m - warm-up
100m - 1:37 (:15 sec rest after each)
100m - 1:40
100m - 1:42
100m - 1:42
100m - 1:38
100m - 1:40
100m - 1:40
100m - 1:39
100m - 1:41 
100m - 1:39
100m - cool down
50m - kick-board
100m - cool down
50m - kick-board
200m - cool down
Hot-Tub 

Again, very surprised that the times for all 10 x 100s were so close to one another. I felt like I was putting out around 85-90% for each 100m, then closer to 90-95% near the end. It's cool to see these times (1:39:80 avg.) compared to my avg. 500m times (1:53). Nice. Eventually, it'd be nice to see the sprint times dropping below 1:30 and closer to 1:20... but that's way down the road and we shouldn't be looking that far ahead while I'm still quite a ways off.

After the swim workout, I headed to the gym and did some light weights and ab work, per my loose plan that is starting to take shape.

I'm on the fence about how to model these sprint workouts. Should I focus on doing the same total workout length and getting faster, or lengthening the number of sprints (to olympic tri distance) to 17 or so and then try to bring the times down from there?