Patrick is speaking of his client WPEngine. I've used them as well at work (likely the same $199/month Business plan for multiple site hosting) and they're pretty good, though according to our Nagios monitoring a site hosted there has had a total of 43 minutes of outages for August which is still 99.9% reliability. WPEngine hosts on Linode and in my experience their magic bullet is, well... no magic bullet. It's still way way better than doing it yourself though and the price you pay for peace of mind is worth it if your site is connected to a revenue-generating activity.
If you want really serious uptime, use something like Jekyll and generate a static site which you host on S3/CloudFront and regenrate only as content changes. You obviously lose some flexibility, but an S3-hosted site is relatively inexpensive for the bandwidth (and do your own math to see if it's worth it for you on the time/money scale) and will handle any load you can throw at it. You can even maintain a crappy unoptimized WordPress installation as the origin server and serve everything up statically from Amazon CloudFront with no load impact to your site.
If you want really serious uptime, use something like Jekyll and generate a static site which you host on S3/CloudFront and regenrate only as content changes. You obviously lose some flexibility, but an S3-hosted site is relatively inexpensive for the bandwidth (and do your own math to see if it's worth it for you on the time/money scale) and will handle any load you can throw at it. You can even maintain a crappy unoptimized WordPress installation as the origin server and serve everything up statically from Amazon CloudFront with no load impact to your site.