CNN  — 

Testing the limits of nostalgia on parallel tracks, “BH90210” – heading into the home stretch of its summer run on Fox – has managed to make a breezy artifact of the 1990s feel kind of sad, while “A Very Brady Renovation,” which premieres this week, takes a ’70s staple and makes it sort of, well, creepy.

In both instances, credit the respective networks and producers for at least trying to do something a little different than the conventional TV reboot. Yet each, in its own way, runs into a brick wall when it comes to having much reason to stick around beyond that initial burst of curiosity, morbid or otherwise.

Granted, the very fact that people (including yours truly) feel compelled to write about about HGTV – the network airing “The Brady Bunch” renovation show – likely counts as a victory. These days, just knifing through the clutter is surely worth something.

Neither show really works, though, in part because they don’t just dabble in nostalgia, but essentially wallow in it.

HGTV got the bright idea of acquiring the Studio City, California, house that provided the exterior for “The Brady Bunch,” paying a hefty premium over the $1.88 million asking price, purchasing the home for $3.5 million.

Maureen McCormick, Christopher Knight, Susan Olsen, Mike Lookinland, Eve Plumb and Barry Williams in front of the original Brady home in Studio City, CA, as seen on 'A Very Brady Renovation.'

The network then enlisted the original “Brady” kids – Barry Williams, Maureen McCormick, Christopher Knight, Eve Plumb, Mike Lookinland and Susan Olsen – to participate in a wholesale renovation of the inside, pairing them with familiar (to viewers of the network, anyway) HGTV stars to transform the home into a replica of the studio set that was used back in the 1970s.

Why? That’s the answer that “A Very Brady Renovation” never fully answers, despite the renovators obsessing over the small details, and the dutiful “Wow!” reactions from the cast – now eligible for AARP membership – about things like making the entryway “very Brady.”

The ostensible rationale is a contest to spend a week in the house, along with six (naturally) guests. It’s a cheeky come-on, but frankly, the $25,000 cash prize sounds more enticing.

Obviously, there’s a lot of goodwill built around the show, which lingered in various forms, from reunion movies and variety specials to a clever 1995 movie send-up. For many, “The Brady Bunch” was a part of childhood, back when blended families seemed more exotic, and an architect dad could comfortably support six kids.

In terms of attention, HGTV has gotten plenty of public-relations bang for its buck, in much the same way that Fox’s “90210” caused a bit of a stir when it made its debut in August. In that case, the show actually reassembled the cast playing slightly jaundiced versions of themselves, reunited in a show about making a revival of “Beverly Hills, 90210,” with all the meta-ness that entails.

"BH90210" airs Wednesday on Fox.

“I miss the ’90s,” Brian Austin Green’s character says in the most recent episode, which basically sums up why the show exists.

Perhaps not surprisingly, though, once the novelty wore off, ratings for “BH90210” have steadily drifted downward, limping toward the final two chapters of the soapy seven-episode engagement.

The fact that the two series will sort of pass in the night – one getting started as the other winds down – is emblematic of the reliance on established titles to stand out from the crowd, although the ’80s have perhaps provided even more inspiration of late, than the decades that bookend it.

Ultimately, these two trips into old zip codes suggest there’s some truth to the notion that building on the past is a way of enticing an audience – and the media – to give your show a look. Getting them to stay interested – especially when there’s so little behind the façade – is clearly another matter.

“A Very Brady Renovation” premieres September 9 at 9 p.m. on HGTV. “BH90210” airs Wednesdays on Fox.