Help needed for Singapore as a stop over ?

Singapore would be a good choice as a stopover point on your long journey and, depending on your interests, might be worth a few days to explore and generally stretch your legs before heading home.
Though it can be an expensive place there are good deals to be had if you simply avoid the high cost areas like the Marina and Orchard Road. Like anywhere else, if you're willing to roam a little further afield the prices go down dramatically. The SMRT (Singapore Mass Rapid Transit) system is fast, efficient, and cheap. So, for that matter, are the taxis which are everywhere. You won't need (nor would you want) a car.
Same thing goes for food. There are plenty of alternatives to a budget busting dinner at Raffles...just need to seek them out. It really is a foodies paradise - the Hawker stalls provide some of the best street food on earth.
It's also a shopper's mecca, with the Marina and Orchard Row areas being the headliners, but a wander around some of the ethnic areas is also enjoyable.
If you're interested in history, recall that the ANZAC's played a major role in the defense of Malaya during WW II, and that the old Changi prison can evoke some powerful memories for those whose grandfathers participated in the fighting of those years. There are tours available that do an excellent job of exploring some of the out-of-the way historical places that most tourists never get to see.
If all you want is to collapse into a real bed after the long flight from Paris you don't even have to leave the airport - there are several transit hotels within the terminal areas.
Safe travels.

I was in Singapore for three days - and wished I had more! There are many things to do and see - some quite unique. Just check out a good guide book or look around online. The main problem with Singapore was that it was HOT! I found that doing some of my sightseeing in the evening was more pleasant because of this.

I purposely splurged on a nice hotel (after three weeks on a hard bed in China, I was ready). But I could have found something quite acceptable for less. I didn't spend much otherwise. There are tons of places to eat, at all budget levels. You can eat really well at Hawker centers. Also the "food courts" in shopping malls are good. There was a large once under my hotel and this is not McDonalds/KFC land! There were many ethnic options and I ate very well there. The subway was easy to use and cheap. I believe that I bought a card where I could add more money onto it. At the end of my trip, I was actually able to get a refund (at the cashier at my last stop) for the unused amount.

I had passed through Changi Airport many times travelling to/from Europe before I finally decided I really should spend some time in Singapore. So in 2014 I spent 4 nights as a stopover on my way to India. It's fantastic and very easy, if somewhat sanitised and homogenised.

My suggestions for sightseeing ...
Raffles & Colonial District
Singapore River - Boat Quay & Clarke Quay
Little India - Mosque & Hindu temple
Chinatown - Chinese temples
Asian Civilizations Museum
Singapore National Museum
Singapore National Gallery
Singapore Botanic Gardens
Singapore Flyer
Marina Bay Sands
Gardens By The Bay
Singapore Zoo

If you are looking for a hotel I can recommend the Fullerton which has a fantastic location by the waterfront and is in the grand old building that used to be the main post office.

thanks everyone for the very useful information, much appreciated.

I know you didn't ask, but have you considered Bangkok? In my experience, it's a lot less expensive than even Hong Kong, never mind Singapore, with lots more to see and do.

Singapore is worth 2 or 3 full days. The street food in it self is enough to occupy your time. It is expensive the accommodation the food isn't.

Singapore is always worth a few days at least. It is the most ethnically mixed place in Asia so the combination of cuisines makes it among the world's very best foodie cities. Such dining adventures don't come cheap and neither do the hotels. Even the beer in the many craft breweries is sold at premium prices. And it will be hot and it will rain, at least briefly. Love it.

We stayed in Singapore for five days prior to our cruise. Loved the city.

I highly recommend the Royal Plaza on Scotts hotel it is a very nice 4.5 star hotel that runs about $175 per night.

Things to do:

City tour including Chinatown, the Gardens on the Bay and Raffles Hotel.
WWII history tour of the island.
Visit the Botanical Gardens and Jurong Bird Park.

thanks for the advice so far, all great suggestions.

Yes, like all the others who have responded, I liked Singapore a lot. It was a 3 day stop over only but we saw a lot. Little India and Chinatown were fascinating, and we took the cable car over to Santosa Island and spent a few hours there. We had a drink at Raffles and felt very Somerset Maughm-ish. But ..... it was unbearably hot for two Canadians from Quebec, I can tell you. The airport, by the way, was the most beautiful I have ever seen.

We found the heat and especially the humidity challenging. We have had 3 stopovers in Singapore on way home from Europe. Take the hop on hop off bus which takes you to all the must see sites. Singapore Botanical Gardens was a highlight for us. Sentosa Island by cable car was also a highlight. Go and see the Gardens by the Bay the Bay sound and light show - spectacular. It is adjacent to the Marina Sands Hotel, which in itself is worth visiting. If you are eating and drinking anywhere near Clarke Quay, get a bank overdraft!

thanks for the replies, does anyone have any further suggestions for accommodation, eg: medium priced hotels ( not high end 5 star but not backbacking etc) in a central/convenient location for looking around the city ( for a couple)
we have booked the flights and have about 3 full days

Suggest looking at www.booking.com and using their map feature to filter places in your price range and also within walking distance of a SMRT station. The city (ie the country) is so small, and so well serviced by the metro, that you can find reasonably priced accommodation away from the high priced areas and still be close to things. Taxi's are relatively cheap too - it really is easy to get around.
One note: ignore the touts as you exit baggage claim who will offer to take you "anywhere in the city" for a fixed price. It's a ripoff - just follow the signs to the regular taxi queue...will save you money, and the door-to-door service (especially fatigued and with luggage) can't be beat.

When we were in Singapore we stayed in quite a posh, almost 5 star hotel only because I had just received a small inheritance, but in wandering around we discovered Little India and some wonderful looking small-ish hotels. If I go back to Singapore ever (not likely unfortunately) Little India is where I will stay. Have a little look.

many thanks for the suggestions thus far, all very good.

Actually, unless you have a lot of luggage, you probably don't need to take a taxi from the airport. The MRT goes right from the airport, and it likely goes anywhere you want to be. Buy a card and load it with a bit of money and you will never have to worry about whether it's 'worth it' to take the MRT for a single stop. Believe me, a few minutes of air conditioning is preferable to the walk!

The ethnic neighborhoods are a treat--Little India, Kampong Glam (the Malay neighborhood) and Chinatown for atmosphere and photography--the 'shop houses' span a number of architectural styles and are unique to Singapore. And let me second earlier comments--Singapore is probably the best eating city in the world on a budget. In the past few years, the best hawker stalls have migrated into the indoor airconditioned hawker stalls. And you will eat fantastic cuisine for less than US fast food! I don't bother with the outdoor hawker stalls anymore--there are so many good indoor ones. If you do visit an outdoor stall, bring tissue packets--you 'reserve' your seat by putting a tissue packet on the table by your seat. (And you will use the tissues, too--no napkins.) Don't bother ordering a Singapore Sling at the Raffles Hotel--not only are they expensive, but they're made from a mix!! If you really want one, try the restaurant at the Singapore Botanic Gardens--they make them from scratch, and it's a nice break during a ramble through the tropical gardens there. And whatever you do, don't miss the Orchid Garden there--literally hundreds of different orchid species.

thanks JER for the great tips, any ideas on the best place/area to stay?

You already have some great advice on Singapore. We loved the city as well.

Recommend the Royal Plaza on Scotts Hotel. It is near the Orchard Road MRT station. We paid about $175 US per night.

We found great tours from Viator.