Take it easy on the ride in. Make is a slow enjoyable casual ride so you don't get too worked up.

Wear different clothes than you plan to wear at work (panniers / backpack to keep the change of clothes in works great)

Then the little sweat you do work up is soaked up in the workout clothes and removed. A simple wipe down with a damp towel is enough to remove what little sweat you have on you.

Work all day, then ride home aggressively for the better workout when there is a shower and clean clothes waiting for you there.

Remember, sweat doesn't smell bad. Sweat that stays on you and dries out smells bad. A little wipe down goes a long way to get rid of the sweaty mess smell, as long as you were clean when you started the morning ride.

I keep a towel in my office to dry off with. I also have the luxury of being able to stay in workout clothes for 15 minutes when I get here so I can cool down before putting work clothes on while I'm still sweating. I realize not everyone can do that.

A thing of baby wipes (the kind you use when changing diapers) work great to get that small sweat residue off your sweatiest areas so you're fresh for the day. They are cheap too.

Biggest thing....once you bike regularly...after a while you'll sweat less. Your body gets used to the workout and you just won't heat up at much. (Note: Does not apply to oppressively hot and humid climates. In some places you're just going to sweat a ton and it's going to be gross without a shower)