Note that d2wi and c2w are not exactly equivalent: d2w will consume trailing whitespace after the second word, while c2w will not. FAFAIK, there is no exact equivalent of d2wi using c. I usually end up using c2aw, but that will also consume any word characters preceding the cursor (not a problem for me since I usually navigate using b and w).
There is a nice chart on this page with a few more inferior/superior motion commands:
http://vimcasts.org/episodes/modal-editing-undo-redo-and-rep...
One problem I commonly see with most vim advice articles is they just have too many tips for the reader to consume at once. But if you just make sure to pick up at least one of the tips, you'll at least gain something.