Actually with handoff technically you can make phone calls from your iPad now. I don't make calls from mine but I do answer them fairly often when I've left my phone in another room. You can also send and receive texts from people who don't have iMessage as well which is nice. Of course, you have to have an iPhone to take advantage of it.
We are an Apple family as well. Three iPad Mini 2, an iPad Air, iPad 4, three iPhone 6's and two iPhone 5's that will soon be activated for the younger two this year. If you have an iPhone it really makes sense to stay with the same ecosystem. You will know how it works right out of the box, will have full access to everything you already own and it's 100% compatable with your phone. Sometimes interchangeable. Last week I downloaded a TV show premiere onto my phone to watch on the treadmill at the gym. I watched 40 out of 70 mins and later when I got home I decided to finish it on my iPad. It was exactly where I'd left off. If I'd been on two different platforms that wouldn't have happened. It's a small thing but a bunch of small things like that add up to a very seemless experience.
I LOVE my iPad Mini 2 and while sometimes I think I'd like to have an Air the portability factor of the mini wins out every time. While I personally prefer to use a dedicated e-reader for long reading sessions I like the fact that I can keep my books on my iPad as well. The Kindle app will sync up with my Voyage so I don't have to hunt to find where I'm at. I use mine for well, everything. Reading, magazines, movies, recipes. I originally got mine when my dad was spending a lot of time in the hospital. I would download my Tv shows, a book or two, movies, magazines and as a bonus could surf the net all in one portable device I can toss in my purse.
We all have 32GB which has been plenty but will still go up to 64 when the time comes. There's never such a thing as too much space. Rumor has it that the new iPads will be announced with the phones this year in the beginning of September instead of October. That means the current models will be dropping at least $100 in price and everyone will have them on sale. I scored my kids 32gb mini 2's for about $250 least year. I would like to say hold out for a couple of weeks but if it turns out they don't announce until Oct. you're looking at a couple of months. In any case they are well worth the price over other tablets IMHO.