Just went through this process myself. You mention you have 1 smartphone with no data plan. I would double check that first. When I recently had my dumb phone die (under warranty) and needed to have a phone in the interim I took one of DH's old smartphone's with me to the Verizon store (our carrier). They ported my number to the smartphone but because it WAS a smartphone I was required to pay the data plan for the duration between the port and when I got my replacement dumb phone (only a couple of days). So you just MAY have a data plan and not be aware????
If that is the case, I would recommend a smartphone as well. If you truly don't have a data plan...and don't want to pay the $$ for one, I would go with a tablet. I'm too cheap to be willing to pay $75/month for a data plan for myself (DH carries 2 smartphones but they are paid for by work/fire co.). I went with the Galaxy tablet (7") as I didn't want the bulk of a 10" and don't anticipate really using it all that much. It was about 1/2 the $$ of a microsoft Surface with enough MS Office apps to satisfy my needs (word; excel; powerpoint). I anticipate my needs to be email and excel when I'm out for extended periods during the day. An hour or 2 here & there while running errands, etc. ...I'm not really going to have the time to deal with it anyhow before I get home. If I'm doing a several hour trip and plan to stop for lunch or a meeting...then I would have the time/need to check those apps. At that point I'll rely on someone's wifi connection being available to me.
I was quite impressed with the Samsung lady at the Best Buy store I went to explaining the differences between e-readers; tablets; etc. to me and what expectations I could have from each. I explained to her what my needs were and my budget considerations and she was extremely knowledgeable and helpful without being condescending at all. I would guess she was 45-55 yr old so 'got' where I (58) was coming from. One of the more techie, younger dudes in the store....not so much. Take that for what it's worth.
If you need to access files from your pc, Skydrive seems to be the best bet. Samsung Galaxy has Dropbox (similar cloud storage to skydrive) as a default. I've loaded skydrive to my pc and it's on my galaxy tab. Can access my excel file with no issue. Still working on my Outlook calendar but haven't made a career out of the tablet yet.
Good luck with your decision.