favorite vinegar and olive oil

I've been using olio santo for everyday use for a long while, and I'm ready to try something new. I'm going to give california olive ranch a try. Verdict still out on what's up next for me and vinegars. Thanks for all the suggestions thus far. Pierino, I totally agree with you on the inauthentic balsamic.

My brand for both is Lucini. They make a great Extra Virgin as well as an amazing Fig Balsamic. With a dollop of dijon it's a great vinaigrette.

I waaaaaayyyy prefer a good Spanish Jerez vinegar to the commercial "balsamic" stuff that is sold in places like Trader Ho's. One label I like a lot is Cepa Vieja. I completely agree with the recs for California Olive Ranch oils. They are one of the larger producers here in California but they produce a very good, consistant product. With small producers, as with wines, the taste can be very different from year to year. The harvest and pressing is now over but a bottle of good oil should last a year from the time it's actually opened. The classic French method is 3 parts oil to 1 part vinegar with maybe a teaspoon of dijon as the emulsifying agent.

It really does depend on what kind of salad you want to make. I love apple cider vinegar for a spinach salad, red wine vinegar for frisée and endive, ditto sherry vinegar, and lemon juice for arugula. It's nice to have a variety of vinegars on hand and figure out what you like best. Oddly enough, balsamic used to be my go-to vinegar, but once I experimented with other ones I rarely use balsamic anymore.
As for olive oil, I think the previous recommendations are right on, although there are an astonishing number of olive oil tasting shops now. It's kind of fun to go and taste different varieties. I don't recommend the flavored olive oils, simply because that indicates to me inferior olive oil that needs added flavors to taste like something.
My favorite dressing, though, is a simple lemon juice, olive oil dressing with a bit of whole grain Dijon mustard, microplaned garlic, salt and pepper. Shake it up in a Mason jar.

I rather like plan 'ol apple cider vinegar on a salad and Spanish olive oil.

It depends on the type of salad I'm making (or other food on which I'm drizzling the vinaigrette), so, e.g., I typically use my homemade cider vinegar (made with unpasteurized and unfiltered organic, kind of sludgy but full of flavor cider from the farmers' market) in salads in which I'm adding apple slices (or, sometimes nuts, or pears). I buy red wine vinegar and white wine vinegar from the Oak Barrel Winemaking shop on San Pablo in Berkeley, in 4-liter (!) jugs (sets me back about $13 apiece). It's great! I have about ten different vinegars (at least) in my pantry, so I tend to grab whatever suits my taste. I buy two kinds of sherry vinegar from the Spanish Table; I like the standard one (not the Ximinez) 1/2 and 1/2 with red wine vinegar in my simplest of salads, especially those made with arugula, which generally describes most weeknight salads here. I like California Olive Ranch's reserve and arbequina, too. For everyday cooking, I usethe Spanish olive oil from Trader Joe's. My sons have lived in Spain on several occasions, each; they confirm that it's just like what they came to like and expect there. I know, you asked about vinaigrettes, but I figured I'd pass that along, anyway. ;o)

If you live in NYC there is a wonderful shop in Chelsea Market called The Filling Station (http://www.thefillingstationnyc.com/). They have a wonderful array of flavored vinegars (balsamics) and evoo. I love their lemongrass-mint white balsamic vinegar

For olive oil, my preference is California Olive Ranch a couple 500ml bottles Limited Reserve and the rest 500 ml Arbequina. I do mail order once a year after the harvest and complete all bottles within a year of pressing. For vinegar, my preference is a good Spanish sherry vinegar, a French tarragon white wine or red Bordeaux. I have tried a few California vinegars, but have not yet found one that tops European imports yet ...