Do you have any specific dates in mind? I can then check in the GDS (it will show up to 9 available seats).
If this is a generic question - they sell upgrades at gate - so even if your flight is wide open, it means nothing. Happened to be once on a WAW-JFK flight that the seat next to me was open until about 40 minutes prior to departure, but then they sold an upgrade, so I had a companion.