I've been biking to work every day in Manhattan for about 2 years (~3.5mi each way). I go from 14th to 70th in about 15-18 minutes. I feel healthier and stronger and it has made a difference in every aspect of my life.

There are two reasonable hills on my way to work (and I'm a sweaty guy) so I've had to learn to deal with the inevitability of sweating.

The NUMBER ONE most important change I made was getting a rack and an Arkel saddle bag. Not carrying my backpack on my back cut down my sweating a TON.

During the winter I wear regular clothing with uniqlo v-neck airsim undershirts. I will sweat a little but generally I shed layers as I get hot. I've switched from cotton shirts and blue jeans to mostly flannel shirts and mostly black jeans -- both of which help to cover any incidental sweat spots. I've also switched to more breathable sneakers for daily use. I'll bring a change of shoes clothes if I need to be dressed fancier.

During the summer, with Manhattan heat and humidity, there's no avoiding getting sweaty. I bring a change of clothes, cool off for 5m after parking my bike and then change and walk into work. Not ideal, but the health and exercise benefits significantly outweigh the downsides.