We have a limited number of “sit down” tables at Kiddush at our shul since most daveners gulp down a piece of kugel and fish while standing and then run home to have lunch with their families. There is one table “reserved” for a “study group” for about 30 minutes and then benches. The other two tables are typically “reserved” for the older daveners who cannot stand easily. When someone has a big simcha (with a correspondingly bigger lunch buffet) we typically have enough tables for sit down.
I’m still not sure I agree with CT Lawyer that a donation for a brass plaque on a bench and shtender gives one permanent chazakah when they are not there. In our shul, about half the benches have a brass plaque in memory of XYZ, but those seats are not treated as a makom kavuah.