If a site needs SSL it should definitely have SSL, no questions asked. But recommending it across the board? I’m dubious.
We work with around 50 clients a year and each site is a minor headache to a full blown nightmare to liaise with SSL signing authorities and clients, and when certificates forget to get renewed it’s not pretty.
Additionally, anecdotally it seems that most websites I visit that do use HTTPS have various errors relating to the SSL or connection (insecure content, expired certificates, dubious certificates, etc). My little address bar padlock is much more often grey (or red) than it is green.
If SSLs were more straightforward (e.g.: self signing, perhaps?) and less costly I’d perhaps suggest all clients should consider it. As it stands at the moment, unless there’s truly secure information being transmitted we’re not likely to do it for a possible, slight, SEO bump and some added end user anonymity.