1) If your CMS just needs to be used in-house, then roll your own. It takes a week or less, you can deep-integrate it into your applications, and you'll be guaranteed to get more or less exactly what you want.
2) If you either need it to be exposed to external/non-technical people or you absolutely do not want to spend time developing CMS features, use WordPress for content pages and your app stack of choice for app pages. You can have them share the same domain if a requirement for e.g. SEO by using reverse proxy tricks -- trivial to Google if you know the words "reverse proxy." If not a requirement, don't do it that way.
One of the nice parts about using WordPress is if you have a high-generalizability problem like "It needs to work on an iPhone" then you are basically guaranteed that some 17 year old designer has hacked together a plugin which makes it mostly work on your iPhone. The downside of using WordPress is that... feel free to rephrase the last sentence.
Do you do what you described in option 1 or 2? I know you use WP for your blog but what do you do for the marketing/landing pages of your apps? Do the marketing pages live in the same code base as the app? I'm inclined to do it this way personally so that integration of something like ABingo! is easier.
The real downside is security. The hardening wordpress[1] article is pretty good but I also found some decent tricks in the .htaccess file for the html5 boilerplate[2] that seem useful too. You end up having to install it, then fix it, which is never good.
[1]http://codex.wordpress.org/Hardening_WordPress [2]https://raw.github.com/h5bp/html5-boilerplate/master/.htacce...
If you want to put in the for to doing some learning Drupal is a good. Its got a massive community. Its not as "plugin" friendly as WordPress and its more server side Dev friendly than WordPress. For my personal use I use Mezzanine which is a Django project. I picked it because its got a lot of solid basics that id need, is python based yet has the backing of Django community.
Unless you roll your own you're always going to become frustrated with a decision that someone else has made for yourself.
It has one of the largest ecosystems (if not the largest), and you can usually find multiple plugins to do whatever you want. You can self host, use their free hosting, or pay for their premium hosting. It has a variety of responsive themes (both free and paid), and a mobile switcher that will auto-detect if you are surfing from a mobile or desktop device. Due to its popularity there's tons of tutorials and help on bunches of forums. It may not be the best if you are looking for a particular feature set, but it is probably the best all-around solution.
Wordpress is wordpress. You're stuck with php and mysql. (ick).
Jekyll is awesome and together with http://prose.io, it's basically a cms.
http://developmentseed.org/blog/2012/07/27/build-cms-free-we...
Small anti WordPress rant... it uses absolute URLs for everything which is a total PIA when moving domains.
I think mezzanine is a great alternative to wordpress. It makes a great blog if that's all you want. If what you need is a CMS to handle the content side of your app, you may want something a little more flexible/light weight.
It's actually going fairly well. There have definitely been some issues, but it's been great.
https://github.com/ecotrust/commonplace
Prose.io is still fairly new, but it's open source and is seeing heavy development.
1)It handles thousands and thousands of users out of the box and saves you masses of time with prototyping, and
2) has over 20,000 plugins (that you can get in and tweak) free for the using or modifying.
3) It's got a security team that is constantly vigilant that sends out security updates for you. (That was one of the big sellers for me.)
4) It's got a bit of a learning curve, but it's truly the swiss army knife of CMS's.
5) Once you've built something in Drupal, your app may seem slow, but then you can performance tune it (and its server) to be very very fast.
6) There's a huge community (the other huge selling point) that is very helpful.
7) There are plenty of nice responsive themes that you can tweak for any device you want.
8) It's very gratifying for developers to create new functionality that's never been built before.
9) It has a very well documented API.
