The auto complete stalls so frequently and for so long, I quit using it altogether.
I've had success with the following using Eclipse (Classic) 3.6.1 on Windows 7 x64.
"A workaround, until the fix is released in 3.6.2 is summarized here: http://groups.google.com/group/android-developers/msg/0f9d2a852e661cba"
(copied for convenience)
"You can replace your /plugins/ org.eclipse.jdt.core_3.6.1.v_A68_R36x.jar plugin with one from http://www.google.com/url?q=http://adt-addons.googlecode.com/svn/patches/org.eclipse.jdt.core_3.6.1.v_A68_R36x.zip&ei=vg5aTf2RIMrUgAeI-qTvDA&sa=X&oi=unauthorizedredirect&ct=targetlink&ust=1297749446528273&usg=AFQjCNFv7FGlTrnoVhRGE35JPjHxOwI_Bw and restart Eclipse. Content Assists will be much better. Just try it. Don't forget backup your original plugins. "