Hardware question for robot

Hey. Im planning to do a simple robot, that avoids obstacles using ultrasonic sensors and can be controlled via Bluetooth. But I would also like to add a LCD screen, that would show the distance or just would say "its safe to go", or maybe even connect a temperature sensor to it, so that i would see my room temperature. My question is, if its possible to do this with Arduino Uno, or should I go for Mega?

My question is, if its possible to do this with Arduino Uno

Certainly.

or should I go for Mega?

They are not much more expensive, and have a lot more memory. The trade-off is that they are larger.