Add and weigh is very helpful as you fill the bowl with ingredients and have less washing up.
I prefer ones with a flat base so I can use my own bowl, the size I want, rather than one with a bowl provided.
I like digital scales, but they need a battery (mind you I'm only on the second battery and the scales are ten plus years old. Your good lady may prefer a dial-type arrangement. Or one that screws to the wall and the flat base folds down. Or old-fashioned ones with weights and a scoop. There are endless possibilities.
Suggest you float a Lakeland catalogue (other kitchenware suppliers are available) under her nose, and start a discreet discussion!