Just bowled the nationals earlier this month. Seemed a tad easier than is past years. I took 4 balls, 3 plus my WD spare ball..
RG Gem - bought this week before going based on reco from the pro shop. It's a beast of a ball and could not figure it out in the team event. However, had a great read in S/D.
GB2 - Best look in team event. Read the pattern well
Motive Tribal Pearl - Tried to play straight up the track, but couldn't get it to hold on the back end. Still love that ball though.
Hope this helps, and GOOD LUCK in Vegas!!