My girlfriend and me are now traveling with the Vaude Space III Light. It is an (too) expensive tent, but we got it for half price. Anyway, the point here is that it has two doors, both with a vestibule big enough to put four panniers and a pair of shoes. We find this arrangement very confortable.
Myself, when I travel alone, like going really light. I would not carry a heavy tent just because of the vestibule. Just a place to leave my shoes is enough. In my experience it doesn't rain a lot in the world. Even now on our tour in the UK we never had to cook in the rain in 2 months. When it rains you almost always find some kind of shelter. Only for a tour in very wet areas, like Carretera Austral, West Coast New Zealand, westcoast Norway or rain season in the tropics I would consider a vestibule. But would you really buy a new tent for that?