Something to keep in mind is it takes some planning and choreography to actually manage cum on face assuming you guys do PIV. I feel like that's a decent alternative (though I've never done it) after a BJ if she's not fond of goo in mouth, but to get out of her, stand up, move near her face, aim somewhere that's not the eyes...all during the time period between when I know I will come, and when I actually do, takes some professional-level coordination. If you guys are using a condom (always recommended with a new partner), that becomes borderline a mission impossible. Tummy, in comparison, is much more manageable. You pull out (+optionally rip out the condom) and let it go.

I would not try any acrobatics the first time for you guys.