Touchscreen advise Arduino

I've build a rallytripmaster based on an arduino uno which 7 segments displays. It works fine, but I want to change the segments to a touchscreen.

Because there seems to be much options, I don't know exactly what to buy.

My questions:

  • there are shields which TFS screens, but the it seems to be hard to get access to the other digital in lines I need to use to connect a magnetic switch to it. What should be a good solution when using shields to get access to pins not used by the shield?

  • Are screens from for example Nextion with a serial interface easy to use and fast to be updated by the arduino?

  • Are screens with an I2C connection better/worse/preferable over serial?

If you have experience with special brands/types, can you share your experience?

Thanks

Twan

The 'Stackable' version of my shield allows access to the unused pins 8).

http://www.utftghl.com/new-shield.html

G