My solution turned out to be remarkably easy because my household is Apple and Amazon. I have iPhones, Macs, an iPad and a Kindle. I had the Kindle reader app on my iOS devices and Macs already, so that would be the obvious choice since I have it and I'm used to using it to read books from the Amazon store.
The Amazon book format (awz) is basically the same as an MOBI file, at least MOBI files that don't have any digital rights management (DRM), which, thankfully, Apress books do not.
And Amazon has a nifty Send to Kindle app for Mac and Windows. You basically drag and drop a file, in my case a .mobi file, on it and it gets uploaded to the Amazon cloud. It took less than a minute to get the books onto my iPad and I didn't have to plug it in to sync! There's also a way to email a file to Amazon, but I find Send to Kindle much easier to use.
And it syncs the last read position across devices just like books from Amazon!
I should point out this is now what I originally tried. After doing a brief Google search on the topic I first tried the eBookMobi app for the iPad. The neat thing about this app is that it reads a ridiculously large number of formats and is compatible with DropBox, so you can put your books into DropBox to get them to your iPad.
My beef with eBookMobi is mostly the result of my using Kindle for iPad so much. I basically can't flip pages with eBookMobi. I hold my iPad in my left hand and use my left thumb to flip pages with the Kindle app. The eBookMobi app requires too much distance to flip so I have to use a finger instead of my thumb, at least given the length of my thumb. And making up/down drags change the screen brightness is infuriating. Half the time I went to flip the page I'd end up changing the brightness. It works, and lots of people like it, so it can't be all bad, but I didn't like it. And it's $ 1.99; the Kindle app is free, and in my opinion, much easier to use.
Also, it's probably not a bad idea to also download the pdf file, just in case. Also, the Kindle reader on the Mac does not support copy and paste, so the pdf is handy, especially for software development books where it's convenient to be able to copy and paste a block of sample code.