IMO this is the most realistic and cost effective solution to problem. Most restaurant POS systems that handles reservation, seating and billing should be able

IMO this is the most realistic and cost effective solution to problem. Most restaurant POS systems that handles reservation, seating and billing should be able to provide needed info. Any RFID or sensor base system will be complex, cumbersome and costly. Any passive sensor will require manual scanning. Any active sensor system with receiver will be expensive specially for restaurant with large seating area. Another option may be an incentive based passive RFID sticker. A guest receives a sticker upon arrival and gets some sort of incentive/reward on scanning the sticker at exit. Then you can capture the time in the restaurant or on the table.