My D is finishing her first year at Carolina, and the Honors College has been a great experience. She has taken five Honors classes ranging in size from 8 to 30. Some are Honors versions of required classes (e.g., English, Accounting) and some are specific to the Honors College. She couldn’t get into every class she wanted for next year because the classes are small (often 15 max). You would likely be able to take Honors versions of basic classes like Calc right away, while you might have to wait for some of the “cooler” classes like American Cyborgs or History of the Devil. A nice surprise was that her non-Honors classes have also been pretty small (25 to 40 students).
The Honors Dorm is nice and there are activities (especially in the beginning of the year) to meet the other SCHC first-years (there were 488 in this most recent class). The location is excellent. For later years, there is on-campus housing tied to Honors (650 Lincoln, which is a new apartment complex, as well as the Horseshoe, which is the heart of campus and harder to get into as they are small buildings). The overall campus is very walkable considering its size. You might want to check if UMD has housing specific to Honors students, what the location is like, and whether it’s available beyond Year 1 if you want to continue to live on campus.
As @scmom12 noted, SCHC’s Honors College is consistently ranked as one of the top public Honors Colleges in the U.S. Admission is very selective, the overall size of the HC is limited, and it is difficult to transfer in because of the number of Honors credits required. I don’t know anything about the Scholars or Honors program at UMD; but one of the reasons the SCHC kids get extra “perks” is because there aren’t that many of them (less than 7% of the undergrad population). Lots of very bright kids are not accepted into the SCHC, so the fact that you were is significant. You will have a chance to shine, but expect to be challenged and to meet many other students as talented as you.
SC was 41% OOS for this past year so you will not feel out of place. While some students go home on the occasional weekend, many in the Honors Dorm are there all the time as they live quite a distance away (my D is from PA, her roommate for next year is from CT, and she has three friends from MD). To get to SC, you can fly into Charlotte and take a shuttle ($55 one-way) or fly into Columbia (sometimes fares are really reasonable). Around Thanksgiving and Spring Break, there are free shuttles to the Columbia airport, and an Uber is about $12. The Amtrak station is within walking distance of campus but the schedules aren’t very convenient (meaning the train leaves and arrives in the middle of the night). My kid is a 10 hour drive also. We drove her down for drop-off and I will pick her up next week. We also drove down, as a family, for a football game in the fall.
You mention going to college with people you’ve known your whole life, but realize that you won’t ever see most of them. It might be nice to have the option to go home when you want, maybe bringing along a new friend, but then you’re missing out on things at school. My D’s roommate lives about 2 hours away from Carolina and she has gone home nearly every weekend. While she is friendly with several students (including my D), she has missed out on football games, parties, dinners out, Saturday mornings at Waffle House, etc. Social life is not the reason to choose a school, but it really is an important aspect of college life.
You have two excellent options. Congratulations.
Just make up your mind to bloom where ever you decide to plant, and best of luck in your decision!