I dont think there is club, but it seems like they have live bar at the lobby lounge. Of course no ice link as well. They have swimming pool. The most benefit to stay this hotel if you like shopping or if you have any occasion in the coex mall , it is really convenient due to the hotel is connect to the coex mall

If I were you, I'd take taxi. If no traffic, the tax costs less than 10,000KRW (according to Naver map, it's about 6KM, less than 10mins). Black/luxury taxi provides better service but is far less common and costs double. And a big IF her is the traffic condition -- the time and fare can easily go up (even double) in peak hours. Subway is convenient especially if to avoid traffic hour -- take Budang line from Suseo, transfer at Seolleung to #2 line, to Samseong station; Grand IC is at exit #5. About 5~6 stops total; short ride but with connection. Another alternative is bus -- many buses run from Suseo to Samseong, if you feel comfortable doing so, or simply adventurous.

if you have more than 1 luggage, arrive in the bad weather, or simply want to avoid walking or any potential mistake, take KAL 6704 -- it drops off/pick up right at the hotel front door; if you are flying with Korean Air, you can purchase the bus ticket (part of duty free) with some discount. CALT 6103 is faster (not stop vs KAL's last stop is Grand IC) and more frequent (10~20min interval vs KAL 30min), but its stop is at the Samsung subway station exit #5, which is closet subway entry, but it still requires about 5 mins walk.