Ride comfort and wheel size

Hi guys,
Hope I can learn something. Recently had my car on for service and they gave me the exact same car as a replacement but only with 17 inch wheels. Driving that around felt so much better than mine. Mine has 19.would that actually make a smoother ride if I swapped out for smaller wheels?
Or is it a sign that my suspension is really stiff? Is there any way of getting that adjusted?

As the tyre size increases the tyre wall decreases thus leaving less rubber for compression to soften the ride if you like,

The reason the tyre wall decreases is to keep the overall tyre size diameter correct otherwise it can affect the gearing and speedo readout

Large diameter wheels usually have tyres with small sidewalls. From a performance driving point of view, this is good, as the sidewalls don't flex, neither does the tread, meaning a big contact patch of tyre on the road & lots of grip. Unfortunately, as the sidewall doesn't flex, this will badly affect the ride, as the tyre will absorb lots of shocks before the suspension sees tem.
As a side-note, Formula One racing cars use the (huge) tyrewall flex as a lot of their suspension!

I've only ever had one car with large wheels/low profile tyres...never again. I'm not enough of a boy racer to accept the bone crushing ride.

I'm not surprised you noticed a big improvement.

compromise and get 18's on it

Although off-topic I think it's relevant so I'll throw it in here:
Another tyre related aspect that ruins the ride of modern cars is Run Flat Tyres. These things has sufficiently tough sidewalls to be able to run safely without inflation, so again, the lack of sidewall flex leads to a horribly hard ride!