When I was pregnant I had this crazy idea that I was going to BF till 6 months, then express and bottle feed in the day, to save embarrassment. Once I discovered how much simpler (if very very time consuming in my case) BF was, I started to rethink. When I started expressing at 4 weeks, and discovered it took me half an hour to get 2-3 oz I realised that this was a stupid, stupid plan for me (and the bottles got swiftly ditched - they weren't helping anyone!)
When DS was a few weeks old and I had found mumsnet, DH and I were talking about how long to carry on. He asked how long I was "supposed" to do it, and I told him WHO said to at least 2. He said, "well that's what you should aim for then, surely" and he has supported me about it.
I fed in public till well past 18mo and never had any comments from strangers (and nothing overtly nasty from people I knew, except looks of exasperation and embarassment from MIL, which I ignored )
The thing to remember is that once you get to 6 months, you've got much more choice. It is much easier to mix feed then - your DC is getting used to all sorts of different ways of taking their food etc. Once you've been going that long your milk supply can stand up to a lot more. IMO although I would encourage BF to at least a year, I'd much rather support someone to maintain some BF than to switch because lots of people claim its easier just to go cold turkey.
I night weaned at around 19mo, which was actually pretty easy, and then once I got pregnant a couple of months later I started cutting down feeds (because of the discomfort). Again this wasn't too traumatic as I was flexible about when I said no, and relied a lot on distraction. Lots of people are only on 2-3 feeds a day by a year, which is when you do generally start getting funny looks (unfortunately). I guess it might be harder earlier on, but if your baby loves BF, its going to be hard to stop too!
DS is now 2.1 and I am 24 weeks with DC2. We've had some tough times during the pregnancy but I'm really glad I changed my mind. Planning to tandem feed these but I have an idea I might want to restrict DS quite a lot!