Glass will break when it falls on the floor of the bathroom - which will inevitably happen during a trip. So plastic, or, if you want to be fancy, metal covered glass.
If you don't want to pay for the shipping and only need a couple, the Container store (assuming you have one nearby) sells colorful and serviceable 5ml plastic travel perfume atomizers.
As for how many, using the usual calculation of 10 sprays per ml, 2 5-ml atomizers are more than enough, unless you want more variety, at which point you should go with a number of vials.
Which ones depends on your taste. I have found a fresh vetiver like Sycomore perfect for travel, because it's fresh yet long lasting and elegant enough also for an evening.