I think in a restaurant setting the games might be a bit much. Favors for guests are definitely the norm these days.
For fun you could do plain white baby t-shirts and have some fabric paints available for guests to write their thoughts to the new mom. For one SIL, we used decorations/paper goods with baby hands as the theme. Favors were home made decorated sugar cookies in small hand shapes placed in celophane baggies available at craft stores. I've received small candles in pink/blue (if gender known) and a couple of candies; small decorative soaps.
Don't make yourself crazy and enjoy being Grandmom! And not trying to pat myself on the back...but made it a point to have special grandmom favors of 'grandmom' picture frames or the like for the grandmom's attending....especially for those first time grandmoms (although even the ones that have several grands liked the grandmom gifts as well).