My mum died about a year ago (dad went in 2010) and once my sister and I had dealt with the estate, sold her flat and split the proceeds 50/50 as per the will, I was left with an amount that would probably greatly exceed the number I'd put on here, but guess what? It doesn't really feel like it's changed that much - or at least not in terms of a massive change in lifestyle.
Don't get me wrong, it's made a difference, but it's more things like clearing my mortgage - had about 5 years to run, fixed rate expired November so inflationary bullet dodged there - and not really being horrified when I found out I needed a new roof yesterday, but in terms of day to day expenditure, nothing much has changed. I think part of that is being absolutely terrified of ballsing up a windfall that'll be a once in a lifetime thing. A bit boring really, but a very good version of boring.
In all honesty I think not having a mortgage payment anymore will make more difference than the lump sum.