IK in Seattle,
Yes, they will give me access. Actually they are supposed to give you access to the Club only if you stay on the Club floors in the new tower. But I've been granted access as a diamond when not on Club floors in the new tower, and the several times they tried to put me in the old tower, they said I would still have access to the Club. I've never stayed in the old tower because I either paid to be upgraded or persuaded them to ug me to the new tower.
In talking with the Grand Club asst. mgr., she did say that there have been complaints from some guests that the Club is too crowded. That has never been my experience however. The club is fairly large, as you know.
So, you can't always talk them into ug you to the new tower (even when there are rooms available), but you should be able to talk them into club access if you are a diamond. Based on my conversation with the Asst. Club Mgr. I think they are trying harder to accomdate upgrades to the new tower for diamonds, due to all the complaints. However, it partially depends on who checks you in.