There is also the 76ers vs Knicks. I know the Knicks have a bit of distance between them and the Suns but if they can get another win or two that should put them far enough away that they won't be able to catch the Suns.
The Grizzlies vs Bulls game is important for the Suns if they hope to overtake Memphis. I looked at their schedule and they could very well extend their losing streak to 30 games if they can't beat Chicago. They play 5 teams that are out of the playoff picture, 2 of those teams are Charlotte and Detroit who could still make the playoffs if they get hot but it's unlikely, the Charlotte game is the 2nd night of a back to back on the road for them. They also play the Nets and Lakers but neither of those teams own their picks so they won't be tanking against the Grizzlies. The most likely win is against Sacramento but if they lose out headed into that game they'll have 29 straight losses and I can't see the Suns matching them at that point. They only have 3 games remaining at that point.
Here is what they'll have left after the Bulls games...
At home vs Denver then @ Brooklyn, @ Philly, @ Charlotte, back home for the Lakers, on the road again @ Minnesota, Portland, @ Utah, @ Portland again, @ New Orleans, Sacramento, Detroit, @Minnesota, and @ Oklahoma City to close out the season.