I have stayed in a fairly large % of what are generally regarded as the 'best' hotels in the world. The list below is therefore more of an emotional one and ignore places like Reethi Rah in the Maldives, Four Seasons Florence etc.
1. Four Seasons Hampshire
This is almost certainly the best run hotel in Britain, and the fact it is 70 minutes drive from our house makes it ideal for a getaway. We came here often before we had the little one, and we've been 3 times in the 14 months since as the pool is great for kids, the restaurants serve free food to under 2's and they have babysitters. Food, spa, rooms, staff are all exceptional. My only niggle is the lack of junior suites - the standard rooms sound big at 45 sq m but are a bit of a squeeze with a cot because the bathrooms are so huge, and the next level up is a full suite at twice the price. However, once you've been here you might as well give up travelling in the UK because you won't better it - and I include Chewton Glen, Whatley Manor, Tresanton and Endsleigh in the list of places not as good.
2. IC LeGrand, Paris
Yes, weird choice, I know - especially as it will never win awards for food or staff. However, this is a truly beautiful property and Royal Ambassadors are always treated well (although free club access has just been dropped). The location cannot be bettered for tourism and it works OK for our French office as well. There is nothing I like better than getting a Eurostar about 4pm, hitting the hotel about 8pm, having an hour or so in the club lounge knocking back the champers and snacks then heading down to my unfailingly beautiful and usually huge room to raid the (free for RA's) mini-bar for more champagne and watch a (free) movie. On leisure trips, the location also allows you to nip back to the lounge for a light lunch and afternoon tea. If you've never stayed here in one of the big rooms (standard rooms are laughably small) or had club access its hard to understand why it works so well, but it does.
3. Mandarin Oriental Chiang Mai, Thailand
We've been here twice. The Four Seasons is arguably better overall but the MO is a lot nearer the city. Until you go here you cannot even begin to understand the astounding level of craftsmanship in the architecture and the amazing working paddy fields throughout the estate. We've also had good upgrades on both visits when booking through Amex Fine Hotels & Resorts into the huge villas - far, far bigger than our house, including a grand piano last time! I could happily go back here once every couple of years - shame its so far away.