Wow Peter, thanks for the props. I really don't consider myself an expert at anything other than eating pizza. That I have down pretty good at this point.
Bicster, If you are looking for a sweet, thin sauce, I think Peter has sent you on a great direction with the Escalon/Stanislaus route. After doing many comparative tests of every brand of tomato I can find, I have come to the conclusion that your best bet for this type of sauce is probably going to be a California tomato. I can at this point say fairly confidently that any Italian, or San Marzano/SM style tomato that is available here in the US is going to have a less sweet flavor. I was surprised to find that in Naples I tried some canned tomatoes that seemed to have the best of both worlds, a slightly sweet taste along with the typical San Marzano flavor. If you do want to try a San Marzano, the sweetest ones I have found over here are Pastene, or Collucio. These are probably the closest in flavor to What I had in Naples, but the texture is way off. I still prefer the La Regina over everything else for San Marzano's in the US, but I would avoid them if you are looking for sweet. They are very "dry" tasting tomatoes. If you can get a fresh can they do have a great texture and flavor that is very similar to what I found in Naples, but less sweet. I also must add here that the La Preferita tomatoes I tried in Naples that I loved are considered by Marco (the real resident expert) to be sub-par when compared to other brands available in the area.
You might be thinking to yourself, why not just buy some of these great San Marzano's and add sugar. Well, my wife prefers a sweet sauce and I have tried on various occasions to add sugar, honey, or corn syrup to good San Marzano's to make her happy. What I have found is that even when you get the sauce to have the right amount of sweet, It ends up tasting like candy. It is just not right. Again, back to Escalon/Stanislaus. Also, if you are in an area that sells Pastene, their Kitchen Ready diced/crushed tomatoes are very similar to a slighly watered down Escalon 6in1 and are much cheaper.
More and more I am beginning to think that getting a fresh can, and one that has not been subjected to extreme heat or cold is maybe even more important than the brand. If you see dust on the fancy cans of tomato at your local Italian specialty store you are better off just buying some Hunts at a normal grocery store. If your normal grocery store has some brand of specialty tomato that is expensive, so no one but you is buying it, it is probably going to be a mushy can and have a funny taste. Recently I placed an order for some peeled Escalon 6in1's, unpeeled 6in1's, and some Bella Rosa concentrated crushed to do some Escalon/stanislaus comparisons with some 7/11 and some Sapitoro etc. I knew as soon as I opened the first can of the Escalon product that something had gone wrong. It turns out every can of Escalon I bought has a funny flavor. I am assuming that it was left in a really hot UPS truck or something since it was late summer when I ordered them. I think this is one of the reasons why we find so many conflicting reports on "the best tomato".
Hopefully you will have better luck than I did with my bad Escalon order and you will get fresh cans. At one time I thought Escalon was better, but after trying many variety's from both of them I can say that my opinion is now that they are dead even in terms of quality, and are fairly interchangeable. At one time I thought I could taste the Stanislaus citric acid, but now I am not sure that I can. They both offer everything from whole tomatoes, to paste, and everything in between. If you want whole tomatoes, I do think the Stanislaus Alta Cucina has the edge over the Escalon Bella Rosa whole peeled, maybe by a lot, but it is hard to tell for sure because of this whole freshness of the can dilemma. If you want crushed tomatoes It seems like the Escalon 6in1 are better than the Stanislaus 7/11.
Since you are looking for a thin sauce you have the option of pureeing whole tomatoes, tomato strips, or even diced or crushed tomatoes in a blender. Many people think this is the best way to make sauce, but I have found that if the goal is a sweet sauce with no chunks in it I am better off starting with concentrated crushed, or even paste. I have also found that if I am going to start from paste/concentrated crushed It is even more important to get a high end brand like Stanislaus/Escalon. Since it is easy to mail order and fairly cheap, my suggestion to you Bicster is to get some of the Bella Rosa Concentrated crushed from Escalon.net. You will have to add water to this, so in the end you will also be saving money. Grab some 6in1's while you are at it because they are really great, but they will be more chunky.
Once you have your tomatoes the other key to a good sauce is getting the right water content. If I just take a can of whole tomatoes, and puree the whole thing it is way too watery. Jeff Varasano, a fellow member has great directions on how to remove unwanted water from a can. Il Pizziolo has suggested adding paste. If you need to add water like you will to a product like Escalon's Bonta, make sure you add enough. If your sauce is to thick it will be gross. If it is to thin it will lack flavor, and moisten your pie too much. When you get the right tomato, and the right water content to your sauce you are 90% there.
I have had amazing sauce with nothing added to the tomatoes but salt. If you are going to add to your tomatoes a great place to start is oregano, basil, fennel, garlic, and olive oil. If you use fresh herbs your sauce will be much better. It is easy to add too much so be careful. Again, the main thing is the right tomatoes from a fresh can and the right water content.
Oh yeah, I almost forgot. Don't cook the sauce if you want your pizza to taste fresh!