Aritzia has a number of "house" lines, and a couple of them (Talula and Talula Babaton, I think?) are significantly more sophisticated than the others (TNA, etc., which are very young and sporty). They also carry some random high-end things like Rachel Comey boots and Rag & Bone jeans.
I used to think I fell *way* outside their target demographic, and avoided it for years, but I went in with my sister this year and was surprised. I've found a couple of amazing items that have been workhorses for me. The salespeople have been exceptional at both locations I've shopped at, too. I was completely expecting snooty young things who wouldn't give me the time of day, but I was wrong! Who knew. Angie's right - leave no retail stone unturned.
Sizing-wise, it depends. The dresses I've tried have been TTS, and I had to size down on my drapey blazer. Other items fit at my usual size, but REALLY didn't flatter. Many, but not all, of their things seem cut for the young, tall and curve-less. I typically try on 10-15 items and find one or two that I love, while the others are immediate, laugh-out-loud worthy NOs. These are all in the aforementioned more sophisticated brands. No clue on the sizing in their younger lines as they don't interest me.
All that to say that it's worth a try.
ETA: Wilfred is one of their nicer lines, too.