rocknbil - 10:45 pm on Feb 1, 2010 (gmt 0)
... size mainly varying from 2 or 3...However, I'm thinking of changing the font face to "Arial".
The combination of these two make me think you are still using <font>?
I use them all (web-safe's only), based on context, and don't have a preference, but do decide one over another depending on context. Verdana has a lower x-height, meaning it takes up more horizontal space than Arial, and tends to "feel" a little more like a display face. So if I want to separate it from a site largely set in Arial/Helvetica, I'll set that in verdana. Don't overlook Tahoma, which is a nice sans-serif font, but use descendant alternate fonts: tahoma, arial, serif.
For large blocks of text, again, context, but especially in large blocks design plays absolutely no part in it (IMO) - it's all about legibility. Sometimes I revert to Times or a variation due to the reasoning that serifs are intended to make text easier to read. (Don't know that I agree, but dat's wut dey tot uz n typography . . . )
For sizing, I found em (the em unit, not "found 'em") too slippery and unpredictable. I usually don't set a global size on body, but do set sizes in percentages on specific elements and element types - general text, 90%, nothing ever smaller than 75% (and then, only if I know no one will ever read it, such as a copyright line, etc.) The only time I resort to pixel sizing is in a constrained space where it has to work nicely with graphics - and even then it's not wise. But I do a lot less wise things.
A small addition to "usually don't set a global size on body" - if you set 90% on body, then 90% on some element within the body, the actual size is 90% of 90%. While you can gauge that visually, it often gives surprising results. I hate surprises, unless they involve exotic cuisine or expensive spirits.
I try to use as little sizing as possible, overall,allowing the natural document flow and the end user determine what is appropriate. I DO check designs when resized/zoomed. Using percentages seems to let that happen well without breaking the layout.