The velvet Touch vibrator was really great for me. It comes in a few colors. It's a simple traditional vibe with steady vibrations that you control with a dial so she can put them really low or high. It's fairly cheap and it'll open the doorway to trying other things.
I also love my Desire by evolved. I love all their traditional vibes made of plastic.
The best suggestion I can make is to stay away from porous materials like TPR or rubber since they can imbalance the vaginal health since bacteria can stay in the material.