Which part(s) of your body respond best visually?

I haven't been able to workout much in the last month due to a stubborn cold/infection or steady parade thereof.  This week I eased back in with a short easy swim and since everything was still okay I went in for one a day later that was longer/faster than I usually do, followed by about half of the nautilus circuit here.  (About 9 machines, 20 minutes.)

The next couple of days I was tired and sore, but this time in the 'good way'.  I have had a few observations about how my body responds to workouts, especially after an unplanned break.

My shoulders, upper back and upper arms seem to respond quickly to workouts.  Being out of the pool for a week didn't cause much in noticeable  losses, but after the longer workout I SWEAR my biceps were more pronounced and everything just feels harder from my belly button up.  I am down about 6-7 pounds from a couple weeks ago, and I have no idea where it went.  

I know I lost weight from lack of appetite and dehydration, but my eating and drinking has been back to normal for over a week and my weight is still down.  I am NOT complaining, but I don't SEE anything different.  If it was all water, shouldn't it pop right back up?

Anyway I've noticed that I have upper arms that respond really quickly to exercise, swelling and firming up nicely.  I've also always had nice calves but they are getting more chiseled from biking. The parts in between, well, are all a lot more 'squishy'.

Last night I told my wife if my butt and gut responded like my biceps and calves she'd have women around her asking "who's your friend...".

So, what really stands out for you?  The training is good for everything and especially things we can't see, but what results do you get on the outside that you can show off or otherwise be most proud of?

-eric