black tie dress code for wedding guests

[Autumn2014]

What would you wear?
wedding in April.
Catholic church ceremony followed by posh hotel country club reception.
Husband going for modern black tie suit.
I'm a size 14, don't like my arms. Pear shaped
Very pale skin and so suit jewel colours not nudes or pastels.
Would it be weird to wear full length in church?
how do you not look like a wannabe bridesmaid?
I presume sequins and sparkles will look too Christmas party?
Thanks in advance

To avoid the bridesmaid look, I would stay clear of a dress in just one colour or accessorise in different colours or maybe find a patterned dress. And a black dress would not look bridesmaidy, maybe not a traditional wedding guest colour but then neither is wearing evening dress to a church wedding!

I think this is lovely but couldn't find much that fitted the bill:
m.johnlewis.com/mt/www.johnlewis.com/phase-eight-collection-8-empire-dress-slate-nude/p1501616?un_jtt_v_pdp=yes&un_jtt_v_from_product=un_product_52#page_loaded

Ive been to a few such weddings. There were a few full length dresses (which I love) but actually a lot of the women dress much the same as they would for any wedding.

navy lace
navy lace sleeves
green
green or plum
forest print
hugo boss