Sandy Lake RV Park is across the street from an amusement park of the same name (and the road both are on). It is where we are at present. It is closer than the ones named above. It is not without amenities (a pool), its great advantage is the easy accessibility of all Dallas and Fort Worth north of Interstate 30 (the old Dallas-Ft. Worth Turnpike). Essentially, it is at the junction of Interstate 35E (Stemmons Expressway) and TX-190 (G.H.W. Bush Turnpike). Those, in turn link up quickly with Interstate 635, TX-114, etc. In short, any activity in D/FW that is a family attraction is easily available from here.
Garland is a straight shot east from this park. Very easy. A little orver 30-minutes.
That said, there are more attractive parks. The City of Grapevine has a park on Lake Grapevine that is said to be quite attractive (according to those who have stayed there; we had a family next to us a month or so back --last time we were here -- who told us about it); but, be warned: with over 100% more rain this year than normal this park was closed due to high water in June.
RVparkreviews.com :: Grapevine, Texas
Garland itself is unattractive in the main, and I am unaware of any RV parks on the northeast side of Dallas.
I would not recommend the park on W. Commerce. Traffic from the Arlington area to Garland is always a concern. Often heavy. Were it me (a Dallas native), I'd take the long route: Interstate 20E to 635N. Allow 1.5-hours travel time, figure on over an hour. Try to avoid the downtown mixmaster. A single problem there (or along I-30; common to both) will ruin a morning or afternoon. 6-million people with 4-million cars in D/FW.