I think pear shapes tend to avoid tight and strapless?? Have a look at Gwok or Trinny and Susannah sites they have excellent advice- colours wise if you want to wear again I would recommend a bright jewel colour that can be worn winter or summer -Sapphire, Emerald etc
I am short (5ft nothing) and size 16 and have bought this dress recently (only mine is a different colour - nude - but think this is actually than mine nicer now and wish I'd seen this one 1st).
This dress seems to work well with my shape anyway. I bought a 16 and it is quite generous. It's silk so feels really lovely. The assymetric bottom is quite flattering on my (chunky) legs too. Disagree with the text saying it'd look good with a cardi though.
What is the occasion though? This isn't 'formal' as in work formal but I bought mine for a formal lunch in July which I think it's spot on for.