Vbrandt

When we priced out flights from CA to EWR it was going to be $1k round trip x4. $4k vs paying $5.50 in tax x4 for using points was a no-brainer.

When we priced out flights from CA to EWR it was going to be $1k round trip x4. $4k vs paying $5.50 in tax x4 for using points was a no-brainer.

When we priced out flights from CA to EWR it was going to be $1k round trip x4. $4k vs paying $5.50 in tax x4 for using points was a no-brainer.

Gives me chills just thinking about the only time my flight was diverted to LGA due to a problem at EWR. Fought my way through horrific traffic to arrive within an hour of embarkation {SHUDDER}

There is no train that goes directly to Laguardia. You can take an LIRR train/subway to somewhere nearby and Uber/Lyft.
If you can spare the extra $$ it's worth the Uber/Lyft for as far as you want to go. I wouldn't take the subway with all of that luggage if I didn't know the area (I do and I wouldn't). The LIRR is fine and an easier option but NOTHING goes to Laguardia.

From Grand Central you can take the #7 train to Queens.    Get off at any of the 3 stations I circled on the #7 line list of stops  and take an Uber/Lyft…it’s not far from LaGuardia (I circled the airport on the “street map”)
the #7 train is underground in Manhattan , and will go above ground in Queens.
your biggest difficulty will be getting the luggage up/down the stairs.   
 

I was also going to suggest the M60 bus from 125st.

It's been awhile since I've been through LGA, but unless things have changed there aren't any train lines that run out there.  My admittedly dated recollection is that from Grand Central you'd take the 6 train to 125 St., then transfer to the M60 bus.  It's a bit of a PITA trip, and I'd much sooner just pay for the Lyft/Uber to get me out there.