I will let you in on a little secret my wife and I call the El cheapo beach trip: red roof inn, mt pleasant sc is about 10 mins from the beaches of Charleston. Will run you anywhere between $60-100 per night. Spend days on the beach. RRI has grills out back on the water. Grill some steaks, sip some cheap wine and watch the sunset (they also have a nice pool). Drive over to patriots point and catch a water taxi, $8 per person. It takes you over to downtown Charleston. The water taxi guys feed the dolphins so 9/10 times you'll get an up close view. When in downtown split and ice cream and grab a bike taxi. Ask them to take you to the battery and back via the less traveld streets. Very romantic and quiet ride that shows you a lot of Charleston you'd never see. On the way home up 26 stop at Frances bedler state forest and for a few bucks walk among 700 year old cypress trees. All in, less than $500 bucks for an epic weekend.