Add number of tables with different seat configuations
ability to add number of tables available rather than total number of seats.
i.e. if you have tables which seat 4, but only 2 people on a booking  it will assign the whole table and not leave those 2 spare seats for someone else to book.
Alternatively, if max persons per person is max table seating, i.e. 6
If only 2 people book, it will block out 6 seats
If 4 people book, it will block out 6 seats, etc

Sean King commented
Restaurants have only a certain number of tables. Let's say you have 10 tables and each table has 4 seats. That is a total number of 40 seats. However, if you have 10 reservations of 2 people, then all tables are booked but the total number of seats taken would be 20. Not limiting the number of reservations makes this plugin unusable for most restaurants.
The ideal would be to have a total number of seats AND a total number of reservations during a specific time period. This way, whichever number is hit first prevents any further reservations.