Keep in mind that MIA is broken into 3 parts, each NOT accessible post-security from each other. AA will arrive on the opposite side of the airport from where VS departs, so you will have to reclear security regardless. If you need to reclaim your bag and check in, that would write off the Admirals Club and CL (the CL is quite nice, but you have to REALLY want to go there knowing it's a solid 20+ minute walk plus security from the VS/DL check in area, and you'd have to do it essentially 3 times from claiming bag to checking in to going to lounge to heading back to go to security).

The Sky Club is pleasant but small, and I have not been to the LATAM lounge. The Turkish Lounge in the G/H area is kind of hard to find (a random upstairs hallway from what looks like a freight elevator), but it was pretty decent. With 4 hours on what I assume is a separate reservation, I'd recommend just checking out the Turkish Lounge or Sky Club (or both) and getting settled in your UC seat early.