You should look for French "bande dessinee" there are plenty of good stuff. One of my favorite is Jean Pierre Gibrat

Check out Maestro from Marvel. I don't know if that's what you're looking for. George Pérez on pencil and ink and Tom Smith on colours. The art really blew me away on this one. Everybody here seems to be mentioning European comics and they're difficult to find. I don't think they'll ever make a mainstream comic like Maestro anymore. Also, Alex Ross is a very famous western comics artist. He paints everything. When he used to draw whole issues and series, the quality was just unbeatable.

A bit late to the party but I have to add EM Carroll's His Face All Red: http://emcarroll.com/comics/faceallred/01.html It's darker in tone but still reminds me of Calvin and Hobbes a bit, in terms of childlike cartoons mixed with beautiful watercolor. The story also uses color quite a bit both for communication and expression of emotions--just a very well done work in my opinion :)

Have a look at Loisel and Tripp's series Magasin General. The colouring contributes immensely to the creation of atmosphere. It is also interesting to see how the colours of the little Canadian village change with the seasons. Truly masterful.

The Calvin and Hobbes watercolors are the best! Bill Watterson is a really amazing artist.

Don Lawrence (UK+NL) was phenomenal in painting with gouache. Many frames of his last ~200 pages of his series 'Storm' are so beautiful & meticulously painted that they were sold as posters. The 'Thorgal' series (BE+FR) and one-off 'Chninkel' by Gzegorz Rosinski has some instances of great beauty, especially the covers. And I agree with the earlier mentions of Blacksad and especially Moebius (his art was used for 'the Fifth Element').

All though Watchmen was made by a big name (DC) the team that made it was very small. The colours are very bright and "neony", but my favourite moments is when there is a tension moment or action where everything has an unatural red tone, adding to the feel of unstableness and danger.

Well, in the Franco-Belgian comics there are a lot of examples of comics with beautiful colours. Offhand, SkyDoll by Barbucci and Canepa comes to mind. Artists trained in the Milanese stable of Disney make spectacular drawings. Barbara Canepa is phenomenal in colouring with ecolines! Other comics I suggest you look at are those painted by Riccardo Federici: spectacular to say the least. I follow him assiduously and I still eat my hands for not being able to attend one of his workshops at the academy of the city where I live. He works by directly colouring his pencils with acrylic, five days for a spectacular finished page.

I don't read that much comic, I like some niche ones... My favourite colour comic has been H.K. series by Kevin Hearult https://www.facebook.com/kevin34herault I love his slick shading. I mainly like the shape language of his machinery designs, robots and guns, very expressive. (Unfortunately this comic is discontinued) He is heavily inspired by Appleseed, which I also like, I found myself love Appleseed 2004 film the most, where the CG reflection stuff is just starting to be used everywhere. I like Shaun Tan's Arrival very much. It's not a "comic", but more like a graphic novel. Shaun Tan's got stunning imagery! Other than that... Some coloured works from Moebius are looking nice as well.

Blacksad (artist is Juanjo Guarnido). Another cat :)

Your example is pretty "flat color", are you asking for the same or are you okay with more "painterly" authors ?

It's a very different style than Calvin and Hobbes, but my favorite comic in color is "The Wrong Place" by Brecht Evens. The paintings in this book are so beautiful and full of details and I love his technique of using gouache and watercolors. Other comic books / graphic novels in color that I like are: "Casa Transparente" by María Luque, "Patience" by Daniel Clowes, "Turing" by Robert Deutsch, "Rosalie Blum" by Camille Jourdy, also Tara Booth.