What are the good reserve units in or around Patuxent, Maryland?

Every unit has potential to be good or even great. I agree with SFC Hunnell, there are no BAD units.
The company is what the command and Soldiers make it.

You could always ask your local retention NCO.

These are some of the units near you-
310th Expeditionary Sustainment Command:
359 TC BN 203 DET (LOG SPT VSL) BALTIMORE MD
359 TC BN 949 CO (FLTG CFT) BALTIMORE MD
359 TC BN 949 AUG TC CO (FLTG CFT) BALTIMORE MD
55th Sustainment Brigade:
275 CSSB 611 CO (FLD SVC)(MOD) BALTIMORE MD
313 TC BN 313 HHD BN (MVT CTL)(EAC) BALTIMORE MD
313 TC BN 199 DET (MVT CTL)(AREA) UPPER MARLBORO MD
313 TC BN 200 DET (MVT CTL)(AREA) BALTIMORE MD
313 TC BN 430 CO (CGO TRF)(ICHO) BALTIMORE MD

It depends on where you are in your career and what you would like to do next.

Good luck.

There is no such thing as a bad unit. It is the Soldiers within the unit that make it good or bad.
What kind of leader are you

Contact the Army Reserve Careers Division (ARCD); they can show you units and vacancies that might meet your criteria.
http://stayarmyreserve.army.mil/region_contact.htm

200th MP CMD is in Fort Meade, not sure how far that is from there.

You trying to get me to give away my age Major? Back in the Olden Days there was Naval Security Group Reserve Detachment, Washington, DC but the NSG doesn't exist anymore (We Navy Spooks ceased to exist, Magically, We Went Poof). Actually my old community has had a few name changes. First Navy Information Warfare Command and now I think they go by the Handle 10th Fleet.

also 1ST Army DIV East is in that area

I am partial to Civil Affairs and know that Majors are sought in Civil Affairs, but expect to be busy in the coming year.

You will make the Army Reserve Great!!! If you must contact PMO at HRC Fort Knox. Potentially you could also go to an Individual Mobilization Augmentee INA position in Military District of Washington MDW. Let me know if that helps please.

Reluctantly I must take a different tack than the others who have answered your question. There are bad units in the Army Reserve. No amount of spin or spit shine will change that fact. The very best thing to do is to utilize the contacts provided by others to find what units are in your specific vicinity. Look at their mission, size, command, composition, location, etc., and if possible visit the unit and see what they have to offer you and what you can offer to them. As an O-4 HR professional, you have the potential to be worth your weight in gold to any unit as it seems most everyone has a shortage in that area. Don't be afraid to reach out geographically or challenge yourself to consider other units. As you meet these units you will get a feel for them and how you can fit in. They will also know of other units in the area and may make you aware of other opportunities. Fort Meade, MD is not too far away as has been mentioned. The Reserves can be a dumping ground for toxic leadership and individuals who have retired in place, and as long as they do the minimum, no one seems to mind. There are a lot of power point rangers and micro managers out there. But there are also a lot of good units that are trying their best with limited resources, funding and equipment. Good Luck!

None of that stuff is near her. Patuxent MD is further south than Waldorf. She'll have about an hour's drive to battle assembly if she comes up to the Fort Meade area.