Like much of LA County. Plenty of LA neighborhoods are technically suburbs just like some LA suburbs are actually in the city limits (Houston has a similar issue).

I think it probably still fits the description of the thread. You guys are getting too hung up on a definition of a suburb.
Other LA metro places that are destinations:
Burbank
Pasadena
Malibu
Anaheim
Manhattan Beach (South Bay)
The OC beach cities; Newport Beach, Huntington Beach, Laguna Beach, San Juan Capistrano.
Places like Palm Springs, Big Bear, Santa Barbara, Ventura, Ojai would fit more into the day trip category.

The historic district in Alexandria is a definitely a nice visit for an afternoon.

The thread might as well be the best metro destinations.The term "suburb" seems to be just a physical characteristic of a place.

Frisco Texas would be an awesome place to live if you cared about a generic suburban lifestyle, Cowboys Training Facility, Stars practice center, FC Dallas stadium, tons of shopping destinatinos, great minor league ballpark, video game museum.

+ Glendale
& to a lesser extent, Woodland Hills

Pasadena for LA. Unlike SM, CC, BH, and WH, it isn’t absorbed by urban LA but rather enjoys a great deal of autonomy. Rose Bowl, Rose Parade, Norton Simon, Caltech, PCC (25,000 students), and Old Town make it significant on a regional, national, and even international level.

For a place that can’t be considered a free-standing city in its own right, I’d go with Malibu, the Beach Cities, and Laguna Beach in OC. Coachella Valley too, although I don’t know if you could call that a suburb of LA. Ditto the Hamptons and NYC.