For your tabular environments, the answer is easy: just change your
\arraystretch after you change your
Notice that it's half of what
\baselinestretch is; so since
\baselinestretch is 2, you need to set
\arraystretch to 0.5 to get it back to 1.
itemize lengths are a bit tricker. Here, I think your best option is the
etoolbox package, which lets you manipulate what happens when an environment is invoked without having to alter the environment itself. Here, I'd use the following:
Or whatever value you think makes it look best. The inter-item spacing would be double, though, unless you also used
enumitem (the package) to change
itemsep, as suggested in one of the comments:
You can massage the spacing until you get what you want, but this seems to be just about right. Here's my complete example document:
One & line \\
Two & lines \\
Three & lines \\
\item One thing here to see what happens.
\item A second thing here; and I'll make sure this one
covers more than one line so that we can confirm the right
thing still happens. It's important, after all.
geometry was included just to make it all fit on one page.) And here's the result: