Just did a day trip to Colonia and LOVED it!! It was absolutely beautiful and enchanting. Would gladly go there again and stay at least one night. We rented a motorbike and did a little tour of all the historical sites. Bring your swimsuit and stop at the beach for a dip, very calm, shallow waters. I highly recommend colonia!!

For those that like larger cities... Montevideo is the alternative for a day trip (I mean alternative as to Colonia).

We also just did a day trip to Colonia. Rented a golf cart (a scooter would've been fine
, but we wanted to be comfortable with our camera equip), toured as many areas as allowed (I think you cannot get on routes 21 and 1 without a car). We were there from 12 to 8. We loved it and highly recomend it.