Hi Greg,
Disclaimer: my background is hosting
Web hosts, ISPs and everyone who requires IP addresses is currently facing the huge shortage of IPv4 addresses left in circulation.
We were smart and made sure we had reserves and used ours conservatively. Others are in not as strong positions.
Google is very aware of the lack of IPv4 and I am positive they don't penalize multiple sites on a single IP, let alone in a range, unless they can tie a number of those sites together and they are doing something very blackhat. Even then, it would take a lot for them to discredit an entire IP address.
I will say that the blackhat marketers typically go for the SEO hosting offerings. Think of all of the less than desirable sites that those IPs have had over the years. In my mind, these IPs will have a much lower trust score than a typically shared IP shared with multiple normal websites or dedicated IPs in well maintained ranges.
My recommendation is to choose a regular web hosting service. Do separate your key sites among multiple servers, or even multiple web hosts so if something goes wrong, not all of your sites are affected. Don't put all of your eggs in one basket.
Good luck with your search,
Matt
