My DD is 2.3 and with every stage I've thought it's the best yet 
As a baby, my DD was never happy being put down to play: I think she felt a combination of anxiety and frustration through babyhood. Each stage seems to have eased that a bit: crawling at 6 months and walking at 11 months both opened up her world, and in both cases she was suddenly much happier, and parenting was easier because I could let her tootle around and entertain herself.
Baby proofing wasn't terribly difficult, because it didn't happen that suddenly (in both cases speed and distance started low and increased slowly over time) so we were able to move things as we saw the dangers. I was never able to leave her for more than a couple of minutes, so I didn't find the need for watchfulness too onerous - perhaps if your baby currently tolerates you going to make a cup of tea / have a shower without her, you'll find it more of a shock!
In terms of activities, we started drawing at about 12 months and painting at 18 months. She's only started getting really interested in art from about 2 though,and now we paint most days. Baking also started becoming interesting rather than damage limitation at about 2.
Petting zoos and excursions to gardens are definitely a nice thing to do from about 12 months - and will be easier when she can walk confidently. Garden centres are also nice, especially if they have fish. I think playgrounds came into their own for us at about 18 months, although we started at about 12 months and I know some people start earlier (perhaps just swings). One of my friends was very adventurous and went all over the place and visited museums pretty much from the start. I found that got much easier at about 2: that seemed to be when DD started getting excited about things like going on trains, seeing different places, having her face painted at a festival etc.
I think 12-18 months is very much a continuation of the first year, where you meet friends and let the babies roll around together, go on short trips to the shops and library, maybe some baby classes if that's your thing, and lots of picnics in the summer. Your DH will have a lovely time,and it's fab that he will get to do that since often only mums get to. You could start introducing him to your mum friends, since I think that having a nice circle of friends to share the days with makes a huge difference.