Here are some results on Uranus. As for Neptune, I have calculated the albedo of the planet both through spectroscopy and photometry.
I'm added as well some graph comparisons with Neptune, which show that Uranus is slightly, but definitely more reflective than Neptune in green, red, and infrared. So this shows that Uranus is going to be perceived as less blue than Neptune, and probably colorless (as I have experimentated it) through big telescopes as the eye is switching to photopic vision, and gets more sensitive to the red emission of the planet.
The photometry is the result of a cross analysis between three stars, as no clear bright reference could be found (to the contrary of Neptune where Beta Aquarii worked very well).
The albedo in the V band is slightly higher than the reference (50% against 49%) and this could be an interesting result, as well as the consequence of the secular brightening of the polar region. I recently took images through photometric filters and the polar region is barely perceptible through Johnson V.