First I think it's necessary to step back and figure out WHY we're all doing this thing called writing and what goals we PERSONALLY are after. Of course, we'd all love to become best sellers (we're human, after all,) but, let's face it, that's like winning the lottery since @95% of writers will NOT be best sellers. My goals are to get my stories out there (thanks, Billie!) and enjoy the bits of 15 seconds of fame that this brings me, to enjoy meeting and talking with the people who like my stories, and, most importantly, to enjoy the work of writing.
A friend of mine in NYC has been writing longer than I and has won an Edgar award (one of the few available strictly for mysteries) AND had an indie published book of hers selected for the NYTimes 10 Notable Books of Summer list, with all the publicity that goes with that. Bottom line, she didn't notice ANY increase in sales. People talked about these achievements, she uses the facts in her bio, but sales were flat.
The moral of the story is to figure out WHY you're in this business in the first place. Know that there are no guarantees of success (if defined strictly by sales figures), that no amount of reviews, prizes, or awards will make that happen automatically because NO ONE knows how to get people to actually BUY your book. Personally, after the GREAT good luck of getting published and working at getting some name recognition (and that's something generally done by what works for YOU: writers' lists like dorothyL with its 3000 members, groups like Sisters in Crime, etc., and internet venues if they're truly popular), then I think it's generally up to the gods to point buyers toward our titles, period, and no amount of money or energy is going to do that for us.
A word of caution: Calculate how much of your time, energy, and money your PR attempts are costing you and go from there.
Also I am leery of the new cottage industry of just anyone suddenly becoming a "reviewer," (and the same goes for "literary agents"), and asking for our books to review with an eye to putting them on their blog that has few if any readers... Think about that and do your homework before sending off these freebies, which are not free to us at all, counting postage, mailer, and book.
We're all lucky to be published authors with a wonderful publisher, period. Most writers never get this far. And we have to do what we can and are able, to give ourselves the best shot at getting our books before appreciative readers. There are no certainties. So do your homework, and talk to everyone, and see what works for you. Maybe you'll be the lucky one!