Aw that is great Xena is happy and settled in her new cage

100cm is that sweet spot for hamsters IMO. Exciting you have a dwarf baby as well now! Actually the recommended size is the same for a dwarf hamster as it is for a syrian hamster! They are just as active, if not more so. So 80 x 50 would be a bit on the small side. However the Savic Plaza is a bit tall for a dwarf hamster (unless you partially turn it into a tank with perspex and have at least 10" of bedding as that effectively reduces the height).
So either a lower 100cm cage or a tank style enclosure would be better - and tank style enclosures can be quite expensive unless you make them.
There are two or three cages suitable. One is the Grosvenor XL which is 100cm but not too tall. However it means there's not a lot of room for deep bedding, so it would mean just having deep bedding at one end - eg by putting cardboard inside the bars at one end to hold the bedding in). The whole top roof opens up.
The other - possibly - is the Pets at home habitat which is the cheapest option at about £55. It's also a 100cm cage that isn't too tall, but it only has two really tiny doors, so it would be very difficult to get a shy hamster out of the cage and you'd be forever having to take the barred top off. So although it's inexpensive, it's really not that accessible. It's worth spending a bit more just for good access and ease of use.
And there's the Omlet cage - which is equivalent floorspace to a savic plaza even though not 100cm wide. It measures 88cm x 56cm. I actually think it's a really nice option for a dwarf hamster as it has scope for deep bedding as well with it's perspex sides. It is quite expensive though - but - there is a 20% off sale at the moment!
I'll link them all below. I've also linked the whole cages list. If you do end up buying a new cage, if you use one of the links from here, the forum gets a commission to help fund the site

But it doesn't cost you any more. Or you might find a good used deal on a Grosvenor XL or Barney somewhere.
Grosvenor XL
Pets at Home Habitat 3
Omlet Hamster cage
The Omlet cage is 20% off at the moment for £135 (it's normally £169) in the sale. It's not cheap but - that price
includes the wheel, which is silent. It's bigger than it looks from this photo - the height makes it look less long but it's also quite wide/deep. It has large front access and part perspex for deeper bedding. A couple of people on here have this cage (
@Tulsi and
@Socks' Mum ), so maybe they could post their photos to show you

And I've seen one in the flesh. I think this or the Grosvenor XL would be good options. Unless you prefer the tank style enclosures like the Bucatstate - they are lovely too - but cost more. And actually they no longer seem to be available from Amazon! So hard to get hold of.
I reviewed it last year
here
This is the Omlet cage
And this is the Grosvenor cage
