Agree with Smooth but the transfer bus from T1 to the central RER is chaotic. Best to make sure your flight lands into T2 which has an 'in-house' TGV / RER station and can be walked to with a trolley if necessary. T1 to T2 transfer can also be a complete pain and can take 30 minuts to an hour. Also the stop is outside and cold/wet if having to wait in the winter.

The T2 route is simple and straightforward but if money is not a problem then use the taxi but be ready to queue. It is far easier.

If it helps this is the number of a taxi driver I use in Paris: Mr Issadi +33(0)6 60 99 96 33 who will pick you up from arrivals if you ook in advance. I have found him reliable. Beware if booking by phone Parisien taxis will frequently charge you the cost of coming to fetch you ie the meter runs from the time they leave till the time they drop you off. If travelling from the airport fix a price in advance.

If this is the Holiday Inn (Holiday Inn Express) I think it is, ie the small one, then go for the highest floor possible facing onto the road directly outside the entrance since this gives a great romantic view of the Eiffel tower lit up at night. Lower floors have this view masked by other buldings.