I have 16 month old twins and a nearly 3 year old. When the twins were young often just getting through the day was enough! Even people very close to us did not realise quite what a juggling act it was. I remember taking them all out to a playground/park thing with my mum when the twins were about 5 months old. Whilst we all had a good time, we paid for it later because they were all overtired and they ended up yelling for hours because they were too tired to sleep. Experiences like that really make you not want to do it again. I think that trip out finally made my mum realise what we were tackling daily, even though she has visited for a couple of days every week since they were born. For the first 9 months or so we pretty much had to stick to a rough rule of being awake for no more than 3 hours between sleeps for the twins. We have not attended family gatherings that would involve whole days out - despite the feeling that we think they think we just can't be bothered. At least mum tries to explain for us !
Now we are in the tricky situation of twins sleeping mornings and 2 year old sleeping afternoons. By the time you fit in food that doesn't leave much time for going out. Also it can be a logistical nightmare collecting enough gear for a day out.
Mostly the only full days we go out are to the grandparents - we usually go after the morning sleep, have a picnic somewhere then get back to their house for the afternoon sleep. Then eat tea and leg it home in time for bed. To do that we have to take 2 travel cots, nappies, clothes etc. In the past we also had to consider bottle feeds etc (before that I also had to lug along the breast pump !).
What suits us best is to go out over lunch - but that really depends on how forgiving you think the people you are visiting are - twins learning to feed themselves can be very messy. Also tackling it on my own is daunting.
Despite what I have said above, most weeks they are taken to a toddler group and a music session, and every other week we go to a coffee group. I usually find it much easier to host the coffee group because then I don't have to juggle sleeping so much.
I think if twins had been my first kids I might not have had the energy or guts to brave toddler groups or other outings. I think having the confidence of being an experienced parent helps.
Also if the husband is working them maybe weekends are sacred - maybe he can't cope with the idea of going out and being friendly to people (even if he would enjoy it when he got there).
I guess in your situation I would talk to your friend. Say you appreciate you can't begin to understand what constraints she has on her days, but that you would like to stay friends. Say that if she doesn't feel up to getting together yet let her know that she can pick it up again in a few months. Contact her every few weeks - she may not have time to pick up the phone to ring you !
Just one more comment - baths in our house are a much more ad hoc thing - it is a logistical nightmare taking at least 2 people and usually ends in me getting soaked. It is certainly not a relaxing experience for any of us (fun maybe). The thought of doing it every night fills me with horror !