I have always been a big fan of Klean Kanteen and use my 16oz insulated stainless steel pint cup on a daily basis. Part of the reason I love the cup is that my drinks stay cold and that I can use the GreenPaxx silicone lid and silicone straw with my cup. The fit is perfect! The lid stays on tight and the silicone straw is wide enough to drink thicker liquids like smoothies no problem. The Klean Kanteen stainless steel cup also only weight 3oz so while still a pint size cup it is light enough for smaller children to use.
A stainless steel cup + silicone lid and straw = no plastic