As a college student, who primarily walks everywhere, I'm thankful for having my iPad everywhere I go. The portability and power really make it super handy to carry around everywhere vs my Macbook. I wouldn't it change it for the world.
Like you, I wear watches, so getting the Watch wasn't something new. The fitness features though are something I have to admit or something I feel I have to adapt to rather than being fully encouraged to do. I'm not motivated to move and complete the Activity rings, or feel entitled to stand up every time the watch tells me to. I kinda just use it to monitor life as it is rather than use it to change my current lifestyle. But that's just me.
If you are actively pursuing a healthier way of living and want a device you help you monitor and achieve that goal, then I definitely recommend getting the Watch. But if you are not actively pursuing a healthier lifestyle, then I don't recommend you spend money the Watch to encourage you to be more active. Once again, this is personal recommendation. I'm sure if I was trying to be healthier the Watch would be a phenomenal companion.
Although I don't use the Watch primarily as a fitness device, I still love it. I use it as a remote for my music and lights, I use it to peek at my RSS feeds, send quick texts, answer phone calls, check email, and check social media. It's all about convenience and personal lifestyle when it comes to the Watch.
As an Apple fanatic, it hurts saying this but it's true: If you are getting started on wearables, start with the less expensive activity trackers like Fitbit. And if you aren't sure of the turn out of your pursuit to be more active, I wouldn't risk spending money on the Watch at the expense of giving up your iPad. I wouldn't sacrifice the convenience of an iPad for the convenience of the Watch. If anything you can return the Watch, but I'm not sure (depending on the model you get) if you can go back to an iPad Air if things don't work out.
Once again, these are my recommendations and experiences. You may have an experience completely different than mine.