For what it's worth, we've never had prints turn yellow in the sun, but we do laminate almost everything we print. These are the standard Avery materials we use, that have given us consistently top-notch results:
- 2900 series high-performance calendered with 2000 series laminate for short/medium term signs
- 1000 series cast with 1300 series laminate for long term signs and vehicles
- 700 series high-performance calendered cut vinyl for short/medium term
- 900 series cast for long-term signs and vehicles
And for really cheap temporary signs, we use Avery 2611 without laminate. Yes, it's technically a wall film, but it works great for anything non-laminated because it's so thick and easy to apply. The removable adhesive hasn't been an issue in our experience.