Hello beharmony, and welcome to the Acton forum.
I am from all appearances the "local" to this location active in this forum at present, so I'll give a little bit of background first.
Acton is a Los Angeles area refuge of the wealthier kind of folk who like the rural ambiance, horses and ranches, but don't want to live too far from the City of Los Angeles. Acton began as a desert mining town that dates to the latter part of the 19th Century, and the place still relies on well water and septic systems. Some residents don't have wells, and get their water by truck.
Surprisingly, the unincorporated town (they have a town council, however) has no chain supermarket (Albertson's was turned down by referendum at least twice at the registered voter level) and has no lodgings for the traveler save what is available for RVs at Thousand Trails, which has a long history of being a well run and respected RV park. Some new ownership of late and pricing structure, so be aware of potential changes. If your relatives live there, they historically have had games and activities for the residents and guests. Link here: http://www.thousandtrails.com/getaways/california/soledadcanyon.asp
Acton has a new Los Angeles County library on Crown Valley Road just north of Sierra Highway. I was very impressed with the operation there on a recent visit. Nice and quiet for reading, and a large community room is there for community use.
You'll notice from the link above they list and link to a number of attractions nearby within a 50 or 75 mile radius. Check them out. I second Frisco_Roadrunner's recommendation to see the William S. Hart County park, this silent western movie star's residence while alive. You do go up the hill, so on really hot days you might want to go early or rethink going there if you are not in that good of physical condition - they have no trams. The roof is new, and the main house is once again open for tours. Nice place to visit and learn something about cowboys, western movies, and the American West. Often overlooked and should be visited by more people, imho. Link here: http://www.hartmuseum.org/
Placerita Canyon State park, operated by Los Angeles County, is at the south end of Placerita Canyon Road off of CA Route 14/Antelope Valley Freeway. It is indeed the first place in California that struck gold (1842), before Sutter's Mill up north! So few visitors to this part of early California. The natural state of the place gives you a good experience of what life was like living here in the Californio time period (the time when residents were born Mexican citizens, but now live under United States rule). Placerita Creek was dry the last time I saw the creekbed a few years ago. Link here: http://www.parks.ca.gov/?page_id=622 and here: http://www.placerita.org/
Other places to visit in the surrounding area of the Antelope Valley: Blackbird Airpark and Joe Davies Heritage Airpark, next to each other on East Avenue P in Palmdale adjacent to US Air Force Plant 42 have great displays of the SR-71 Blackbird, B-52, F-104, B-2 Bomber, T-38 trainer, Lockheed L-1011 (undergoing renovation presently) and many more aircraft. Links here: http://www.aviationmuseum.eu/World/North_America/USA/California/Palmdale/Blackbird_Airpark_Museum.htm and http://www.aviationmuseum.eu/World/North_America/USA/California/Palmdale/Blackbird_Airpark_Museum.htm Notice the Friday, Saturday, and Sunday operating days and daytime hours. Docents onsite. . . some of them actually flew or worked on these planes! Gift shop also onsite. Free. Note that Blackbird Airpark's address is *2*620 East Avenue P. . . a typo from the .eu site, so it's next to the Heritage Airpark at 2001 East Avenue P. Trust me. . . I see it every day.
A trip to visually picturesque Vasquez Rocks in Agua Dulce just to see them is wonderful. This is the site of many film shoots (Star Trek, The Flinstones, The Lone Ranger and many more) and will be easily recognizable to many film fans. Great spot for picnic and if you wish, some hiking. Caution: know where you are going when on the rocks. . . and how to get back to your car! This is a red sandstone rock formation in the San Andreas fault zone where the notorious Californio Tiburcio Vasquez hid from the law in the later part of the 19th Century. Link here: http://parks.lacounty.gov/wps/portal/dpr/Parks/Vasquez_Rocks_Natural_Area
Devil's Punchbowl in the Pearblossom area of the Antelope Valley proper is a great place to go hiking. You say you're not hikers, though. Good to explore a bit if you want. Link here: http://www.devils-punchbowl.com/
Charlie Brown Farms in Littlerock at Pearblossom Highway and 82nd Street East is a local "roadie" emporium general store of sorts, and a favorite of many folks from LA on their way to Las Vegas and Arizona. Eclectic displays of every schlocky item you can think of. . . whole rooms devoted to life size mannequin replicas of princes and princesses, pirates and naval officers, Betty Boop. . . that kind of thing. Fascinating. All kinds of smaller knickknacks, and of course peanut brittle, locally sourced raw honey (clarified and pure if desired), local peaches, pears, and apples, and some varieties of produce you'll see no where else - *plus* a a barbeque take out or eat in restaurant serving buffalo burgers, ostrich burgers, and California Santa Maria style tri-tip beef (yum!) are just a few of the items on the menu. Don't leave without a date! (shake, that is) Fun place that is a throwback to the kind of traveler's stands Historic US Route 66 had back in the mid 20th Century. Worth the stop to kill a half hour. . . or several more. It's addicting, and grows on you. Link here: http://www.charliebrownfarms.com/
That's all I can think of off the top of my head. Should you need more, please feel free to respond on this thread and I or another forum member will be glad to assist. Acton was overdue for a more than decent writeup on the forum here, so I spent some more time in my response. I think the information supplied here will be of great help to you and other forum readers.